Let’s solve each problem one by one, step by step.
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Problem 1:
There are 4.5 litres of milk in a pot. The chef stirs in 2.5 g of salt and 1.2 litres of water. How much liquid is in the pot?
Wait — notice something important:
salt is measured in grams (g), which is weight, not volume. But the question asks for “how much
liquid” is in the pot.
Liquids here are milk and water. Salt is solid — even though it dissolves, it doesn’t add to the *volume* of liquid in a simple way (and at this grade level, we usually ignore that). So we only add the volumes of the liquids:
Milk = 4.5 L
Water = 1.2 L
Total liquid = 4.5 + 1.2 =
5.7 litres
✔ We ignore the salt because it’s not a liquid and doesn’t change the total liquid volume in basic math problems like this.
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Problem 2:
The chef took out 54.8 g of butter but then found out that he took out 6.9 g of butter more than he needed. How much butter did he need?
He took out too much — 6.9 g extra. So to find how much he actually needed, subtract the extra amount from what he took:
Needed = Took out – Extra
Needed = 54.8 – 6.9
Let’s calculate:
54.8
– 6.9
______
Start from the right: 8 – 9 → can’t do, so borrow.
18 – 9 = 9
Then 3 (since we borrowed) – 6 → can’t do, borrow again.
13 – 6 = 7
Then 4 (after borrowing) remains.
So: 54.8 – 6.9 =
47.9
✔ He needed 47.9 grams of butter.
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Problem 3:
The chef is making 10.5 batches of dinner rolls. For each batch, he kneaded dough for 0.7 hours and let the dough rest for 1.6 hours. Then he baked the dough for 0.4 hours. How long does it take to make each batch of dinner rolls?
Wait — read carefully: “How long does it take to make
each batch?”
That means we don’t care about 10.5 batches — that might be a trick! The question is asking for time per batch.
For
one batch:
Knead: 0.7 hours
Rest: 1.6 hours
Bake: 0.4 hours
Add them up:
0.7 + 1.6 = 2.3
2.3 + 0.4 =
2.7 hours
✔ Each batch takes 2.7 hours.
(Note: If the question had asked for total time for all 10.5 batches, we’d multiply 2.7 × 10.5 — but it didn’t.)
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Final Answer:
1. 5.7 litres
2. 47.9 g
3. 2.7 hours
Parent Tip: Review the logic above to help your child master the concept of decimal word problem worksheet 5th grade.
