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Calculation of the volume of an irregular shape made up of two connected rectangular prisms.

Volume of an irregular shape composed of two rectangular prisms, with dimensions labeled as 3 in, 5 in, 10 in, 12 in, and a volume of 150 in³ for the first part.

Volume of an irregular shape composed of two rectangular prisms, with dimensions labeled as 3 in, 5 in, 10 in, 12 in, and a volume of 150 in³ for the first part.

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Show Answer Key & Explanations Step-by-step solution for: Volume of irregular shapes (5.MD.C.5c)
Let’s solve this step by step.

We are given an irregular 3D shape made of two rectangular prisms stuck together. We need to find the total volume.

First, look at the left part:
- It has dimensions: length = 10 in., width = 5 in., height = 3 in.
- Volume of a rectangular prism = length × width × height
- So, volume of left part = 10 × 5 × 3 = 150 in³ (which matches what’s written on the image — good!)

Now, look at the right part:
- It shares the same height and depth as the left part? Let’s check.
- The right part extends 4 inches forward (that’s its length).
- Its width is still 5 in. (same as left part — they’re connected side by side).
- Its height is 3 in. (same as left part — top surfaces are aligned).
Wait — actually, looking again: the label “12 in.” is along the top edge of the whole shape. That means the total length from front to back is 12 in.

But the left block is only 10 in. long. So the right block must be 12 - 10 = 2 in. long? Wait — no, that doesn’t match the “4 in.” label.

Actually, let’s reorient:

The diagram shows:
- Left block: labeled with 10 in. (length), 5 in. (width/depth), 3 in. (height) → volume = 150 in³ ✔️
- Right block: labeled with 4 in. (this is likely its length extending beyond the left block), and it shares the same 5 in. depth and 3 in. height.

But wait — if the total length is 12 in., and the left block is 10 in., then the right block should be 2 in. long? But it says 4 in. Hmm.

Actually, maybe the 12 in. is the total length of the entire shape from left to right? No — the 10 in. is labeled on the left block’s top edge, and 12 in. is labeled on the right block’s top edge? That doesn’t make sense.

Wait — let’s read the labels carefully:

From the image description:
- Left block: 10 in. (top edge), 5 in. (side depth), 3 in. (height) → volume 150 in³
- Right block: 4 in. (its own length?), and 12 in. is labeled on the top edge of the right block? Or is 12 in. the total?

Actually, looking at standard problems like this: often the 12 in. is the total length of the combined shape. But here, the left block is 10 in., so if total is 12 in., the right block would be 2 in. — but it says 4 in.

Alternative interpretation:

Maybe the 12 in. is the length of the right block? But that would make the total length 10 + 12 = 22 in.? That seems too big.

Wait — perhaps the 4 in. is the width (depth) of the right block? But the left block is 5 in. deep — that wouldn’t match.

Let me think differently.

In many such diagrams, when two blocks are joined, they share a common face. Here, the left block is 10 in. long, 5 in. wide, 3 in. high.

The right block is attached to the end of the left block. The label “4 in.” is probably the length of the right block (extending further). And “12 in.” might be a red herring or mislabeled? But that can’t be.

Wait — another possibility: the 12 in. is the total length from the very front to the very back? But the left block is 10 in., so if the right block sticks out 4 in., total would be 14 in.? Not matching.

Perhaps the 12 in. is the length of the right block? Then total length = 10 + 12 = 22 in.? But why label 4 in.?

I think I see the issue. Looking at typical textbook problems: often the "12 in." is the total length of the entire composite shape. But here, the left block is 10 in., so the right block must be 2 in. long. But the diagram says "4 in." for the right block.

Unless... the 4 in. is not the length, but the width? But the left block is 5 in. wide — if the right block is 4 in. wide, then they don't align.

Wait — let's calculate based on what makes sense.

Given that the left block volume is 150 in³ = 10 × 5 × 3, that’s correct.

For the right block, if it has the same height (3 in.) and same depth (5 in.), and its length is 4 in., then its volume would be 4 × 5 × 3 = 60 in³.

Then total volume = 150 + 60 = 210 in³.

But what about the "12 in." label? If the left block is 10 in. long and the right block is 4 in. long, total length would be 14 in., not 12. So that doesn't match.

Alternative: perhaps the 12 in. is the length of the right block, and the 4 in. is something else? But the diagram says "4 in." next to the right block's end.

Another idea: maybe the 12 in. is the total length, and the left block is 10 in., so the right block is 2 in. long. Then volume of right block = 2 × 5 × 3 = 30 in³, total = 180 in³. But then why is "4 in." labeled?

Perhaps the 4 in. is the height? But the height is already given as 3 in. for the left block, and they appear to be the same height.

I think there might be a mislabeling in my understanding. Let me try to visualize:

Imagine the shape: it's like an L-shape or a T-shape? From the description, it's two rectangles joined.

Standard problem: often, the "12 in." is the total length, and the left part is 10 in., so the overhang is 2 in. But here it says 4 in.

Wait — perhaps the 4 in. is the width of the right block, and it's centered or something? But that complicates things.

Let's look for clues. The user said "Volume of an irregular shape", and gave dimensions.

Perhaps the 12 in. is irrelevant? But that can't be.

Another thought: maybe the 12 in. is the length of the right block, and the 4 in. is the distance from the end or something. But that doesn't help.

Let's calculate both ways and see which makes sense.

Option 1: Right block length = 4 in., same width 5 in., height 3 in. → volume = 4*5*3 = 60 in³. Total = 150 + 60 = 210 in³.

Option 2: Total length = 12 in., left block 10 in., so right block length = 2 in. → volume = 2*5*3 = 30 in³. Total = 180 in³.

Which one is intended? The diagram has "4 in." labeled on the right block, and "12 in." also on the top. Perhaps the 12 in. is the length of the right block? But then why label 4 in.?

I recall that in some diagrams, the number on the top edge might be the total, but here it's placed on the right block.

Perhaps the 12 in. is a mistake, and it should be 14 in. for total length. But we have to work with what's given.

Let's think about the position. If the left block is 10 in. long, and the right block is attached and extends 4 in. beyond, then the total length is 14 in. But the diagram says 12 in. on the top of the right block — that might mean the right block itself is 12 in. long? But then the 4 in. is confusing.

Another idea: perhaps the 4 in. is the width (depth) of the right block, while the left block is 5 in. deep. But then they are not aligned, and the volume calculation would be different.

For example, if the right block has depth 4 in., length say L, height 3 in., but what is L? If total length is 12 in., and left is 10 in., then right is 2 in. long, so volume = 2 * 4 * 3 = 24 in³, total = 174 in³. But that seems arbitrary.

I think the most reasonable assumption is that the two blocks share the same depth and height, and the "4 in." is the length of the right block, and the "12 in." is either a distractor or mislabeled. But that can't be.

Let's search for similar problems online or in memory. In many textbooks, when you have two rectangular prisms joined, and one is labeled with its own dimensions, you use those.

Here, the left block is fully dimensioned: 10x5x3=150.

The right block has "4 in." labeled, and since it's attached, likely it has the same height 3 in. and same depth 5 in., so volume = 4*5*3 = 60.

Total = 210.

And the "12 in." might be the total length, but 10+4=14, not 12, so perhaps it's a typo, or perhaps the 12 in. is for something else.

Another possibility: the 12 in. is the length from the start of the left block to the end of the right block, but the left block is not starting at zero? That doesn't make sense.

Perhaps the left block is 10 in., but it's inset, and the right block is 12 in. long, overlapping or something. But the diagram shows them adjacent.

I think I need to go with the most straightforward interpretation: the right block has length 4 in., width 5 in., height 3 in., so volume 60 in³, total 210 in³.

But let's double-check with the 12 in. If the total length is 12 in., and the left block is 10 in., then the right block must be 2 in. long. Then why is "4 in." labeled? Unless "4 in." is the width.

Suppose the right block has width 4 in. (instead of 5 in.), and length 2 in. (since 12-10=2), height 3 in., then volume = 2*4*3 = 24 in³, total = 174 in³.

But that seems less likely because usually the depth is the same unless specified.

Perhaps the 4 in. is the height, but the left block is 3 in. high, so that doesn't match.

I recall that in some diagrams, the number on the side might be the dimension perpendicular. Let's assume that the "4 in." is the length of the right block, and ignore the 12 in. for now, or consider that 12 in. is the total, but then it conflicts.

Another idea: perhaps the 12 in. is the length of the right block, and the 4 in. is the amount it overlaps or something. But that's complicated.

Let's calculate the volume using the given numbers without assuming.

The shape can be seen as a large rectangular prism minus a smaller one, but it's additive.

Perhaps the 12 in. is the total length, and the left block is 10 in., so the right block is 2 in. long, and the "4 in." is a label for the depth of the right block, but the left block is 5 in. deep, so the right block is narrower.

In that case, volume of right block = length * width * height = 2 * 4 * 3 = 24 in³.

Total volume = 150 + 24 = 174 in³.

But is that standard? Usually, if the depth changes, it's specified.

Perhaps the 4 in. is the height, but then the left block is 3 in. high, so the right block is taller, but the diagram shows them at the same height.

I think I found a better way: in the image, the "12 in." is labeled on the top edge of the right block, which suggests that the right block's length is 12 in. But then the left block is 10 in., so if they are joined end to end, total length is 22 in., and the "4 in." might be the width or something else.

This is confusing.

Let's look for the most logical solution. Perhaps the "4 in." is the additional length, and "12 in." is the total, but 10 + 4 = 14 ≠ 12, so not.

Another thought: maybe the left block is 10 in. long, but the 12 in. includes the right block's length, and the 4 in. is the width of the right block.

Assume that the right block has length L, width W, height H.

From the diagram, height is 3 in. for both.

Depth: left block is 5 in., right block might be different.

If the total length is 12 in., and left block is 10 in., then right block length = 2 in.

If the "4 in." is the width of the right block, then volume = 2 * 4 * 3 = 24 in³.

Total = 150 + 24 = 174 in³.

If the "4 in." is the length, and total is 14 in., but labeled 12 in., perhaps it's a typo, and it should be 14 in.

But in many online sources, for similar problems, when they give "4 in." for the extension, and total is not given, they use 4 in. as the length of the second block.

Moreover, the left block volume is given as 150, which is 10*5*3, so for consistency, the right block should be 4*5*3 = 60, total 210.

And the "12 in." might be a mistake, or perhaps it's the length from the beginning to the end of the right block, but if left is 10 and right is 4, it should be 14, so maybe it's 14, and "12" is a typo.

Perhaps the 12 in. is the perimeter or something, but that doesn't make sense.

I think for the sake of solving, I'll go with 210 in³, as it's the most straightforward.

But let's verify with another approach.

Suppose we consider the entire shape as a single prism with a cutout, but it's easier to add.

Perhaps the 12 in. is the length of the right block, and the 4 in. is the distance from the joint or something.

I recall that in some diagrams, the number on the top might be the total, but here it's placed on the right block.

Let's assume that the right block has dimensions: length = 4 in., width = 5 in., height = 3 in., so volume 60 in³.

Total volume = 150 + 60 = 210 in³.

And the "12 in." might be irrelevant or a distractor, but that's unlikely.

Another idea: perhaps the 12 in. is the length of the left block plus part of the right, but that doesn't help.

Let's calculate the volume if the right block is 12 in. long: 12*5*3 = 180 in³, total 150+180=330, but then what is 4 in.?

If 4 in. is the width, then 12*4*3 = 144, total 294, still not nice.

Perhaps the shape is not two separate blocks, but one block with a protrusion.

I think I need to accept that the intended answer is 210 in³, with right block 4x5x3.

Or perhaps the 4 in. is the height, but then it's inconsistent.

Let's look at the image description again: "4 in." is labeled on the right end, "12 in." on the top of the right block, "10 in." on the top of the left block, "3 in." height, "5 in." depth for left block.

Perhaps the 12 in. is the total length, and the left block is 10 in., so the right block is 2 in. long, and the "4 in." is the width of the right block, while the left block is 5 in. wide.

In that case, volume of right block = 2 * 4 * 3 = 24 in³.

Total = 150 + 24 = 174 in³.

This is possible, and 174 is a nice number.

If the right block has the same width 5 in., then 2*5*3=30, total 180.

But why label "4 in." if it's 5 in.?

Unless "4 in." is for something else.

Perhaps "4 in." is the height of the right block, but the left is 3 in., so the right is taller, but the diagram shows them at the same level.

I think the best bet is to assume that the right block has length 4 in., same width 5 in., same height 3 in., so volume 60 in³, total 210 in³.

And the "12 in." might be a mislabel or for another purpose.

Perhaps the 12 in. is the length from the start to the end, but the left block starts after 2 in. or something, but that's complicated.

Let's do this: suppose the total length is 12 in., and the left block is 10 in. long, but it is positioned such that it starts at x=2, ends at x=12, so length 10 in., and the right block is from x=0 to x=4, so length 4 in., and they overlap from x=2 to x=4.

Then the combined shape has length from 0 to 12, but with overlap.

Volume would be volume of left + volume of right - volume of overlap.

Left block: 10*5*3 = 150

Right block: 4*5*3 = 60

Overlap: from x=2 to x=4, so length 2 in., width 5 in., height 3 in., volume 2*5*3 = 30

So total volume = 150 + 60 - 30 = 180 in³.

Oh! That makes sense. And the total length is 12 in. (from 0 to 12), left block from 2 to 12 (10 in.), right block from 0 to 4 (4 in.), overlap from 2 to 4 (2 in.).

Perfect! So the "12 in." is the total length, "10 in." is the length of the left block, "4 in." is the length of the right block, and they overlap by 2 in.

So volume = V_left + V_right - V_overlap = 150 + 60 - 30 = 180 in³.

And the overlap volume is 2*5*3=30, since same width and height.

So total volume is 180 in³.

This resolves all labels: 12 in. total length, 10 in. left block, 4 in. right block, and they overlap.

In the diagram, it might show them sharing a common section.

So final answer should be 180 in³.

Let me confirm:

- Left block: positions x=2 to x=12, y=0 to 5, z=0 to 3 → volume 10*5*3=150

- Right block: x=0 to x=4, y=0 to 5, z=0 to 3 → volume 4*5*3=60

- Overlap: x=2 to x=4, y=0 to 5, z=0 to 3 → volume 2*5*3=30

- Union volume = 150 + 60 - 30 = 180 in³

Yes, that works.

If they didn't overlap, total length would be 14 in., but it's 12 in., so overlap is necessary.

So the correct total volume is 180 cubic inches.

Final Answer: 180
Parent Tip: Review the logic above to help your child master the concept of finding volume of irregular shapes worksheet.
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