Question

The Johnson family lives 432 miles from the beach. They drive 52% of the distance before stopping for lunch. About how many miles do they drive before lunch? Explain how you can use mental math to find the answer.​

Answer 1

To find the distance the Johnson family drives before stopping for lunch, we can multiply the total distance to the beach by the percentage of the distance they drive before stopping for lunch.

52% of 432 miles can be found by multiplying 0.52 by 432:

0.52 * 432 = 224.64 miles

To use mental math to find the answer, we can round 432 to 400, which makes the calculation easier.

52% of 400 can be found by multiplying 0.5 by 400 and adding 2% of 400:

0.5 * 400 + 0.02 * 400 = 200 + 8 = 208 miles

Then, we can adjust for the fact that we rounded 432 to 400 by adding 32/400, which is 0.08, to the result:

208 + 0.08 * 432 = 208 + 34.56 = 242.56 miles

Therefore, the Johnson family drives about 242.56 miles before stopping for lunch.