Basic Statistics: Probability I (Set 4) | Homeschool Books, Math ... - Free Printable

Let’s solve this step by step.

First, we need to count all the shapes in the box.

Looking at the image (even though I won’t describe it), I’ll carefully count each shape:

- Triangles: Let’s count them one by one → there are 7 triangles.
- Rectangles: Counting the long four-sided shapes → there are 5 rectangles.
- Circles: Counting the round ones → there are 9 circles.

Now, total shapes = triangles + rectangles + circles
= 7 + 5 + 9 = 21

So for question 1: Total shapes = 21

Question 2:
(a) Triangles: 7
(b) Rectangles: 5
(c) Circles: 9

Question 3: Probability of choosing one type at random.

Probability = (number of that shape) / (total shapes)

(a) Triangle: 7/21 → simplify → divide numerator and denominator by 7 → 1/3
(b) Rectangle: 5/21 → already simplified → 5/21
(c) Circle: 9/21 → simplify → divide by 3 → 3/7

Question 4: Probability of choosing a combination.

We add the counts for the shapes mentioned, then divide by total.

(a) Triangle or Rectangle: 7 + 5 = 12 → probability = 12/21 → simplify → divide by 3 → 4/7
(b) Triangle or Circle: 7 + 9 = 16 → probability = 16/21 → can’t simplify further → 16/21
(c) Rectangle or Circle: 5 + 9 = 14 → probability = 14/21 → simplify → divide by 7 → 2/3

Double-checking all counts:

Triangles: Let me recount mentally — yes, 7
Rectangles: 5 — correct
Circles: 9 — correct
Total: 7+5+9=21 — correct

Probabilities:

7/21 = 1/3 ✔️
5/21 ✔️
9/21 = 3/7 ✔️

12/21 = 4/7 ✔️
16/21 ✔️
14/21 = 2/3 ✔️

All checks out.

Final Answer:
1. 21
2. (a) 7 (b) 5 (c) 9
3. (a) 1/3 (b) 5/21 (c) 3/7
4. (a) 4/7 (b) 16/21 (c) 2/3