Question

Which is a good comparison of the estimated sum and the actual sum of 7 9/12 + 2 11/12?

Answer 1

7 9/12 + 2 11/12
((12*7)+9)/12+((12*2)+11)/12

93/12+35/12

128/12 divide by 2

(128/2)/(12/2)

64/6 divide by 2

(64/2)/(6/2)

32/3

10 2/3

Answer 2

7 9/12 = 7.75
2 11/12 = 2.917

So we can round both of these up.

7.75 rounds to 8
2.917 rounds to 3

8 + 3 = 11

So the estimated sum is 11.

7 9/12 + 2 11/12 = 10 2/3

So the actual sum is 10 2/3.

The estimated sum is a pretty good estimate to the original number.