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

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

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.