Question

Which of the following is the best estimate of 5 and three-eighths minus 1 and nine-tenths?

4 and one-half

2 and one-half

3 and one-half

4

Answer 1

This might depend on the required level of accuracy.

Start with a sort of gross estimate. 5 and a half minus two is about 3 and a half.

We can refine that a little by saying our starting number was an eighth less than our rounded starting number, but we only took away a tenth less than the actual value. The difference between an eighth and a tenth is pretty small (about a fortieth) so we might be happy with our original estimate.

If we want to really refine it, we will find the exact answer to be a fortieth less than three and a half, or three and nineteen fortieths.

Answer 2

uhhh so its A?

Answer 3

yes