Write and solve an equation to find the value of the variable.

5.2, 8.3, 8.5, 7.7, 7.8, y; mean = 7.1

5.1
5.3
5.8
3.9

The equation can be compiled as;

(5.2 + 8.3 + 8.5 + 7.7 + 7.8 + y) / 6 = 7.1

The mean of 6 numbers is 7.1.

5.2 + 8.3 + 8.5 + 7.7 + 7.8 + y = 7.1 x 6

37.5 + y = 42.6

y = 42.6 – 37.5

y = 5.1

So 1st option is correct.  

1/4 and 8/3 because:

the reciprocal if 4 is 1/4 because 4 is used as 4/1 and the opposite of that is 1/4. the opposite of 3/8 is 8/3 so that is the answer.

12cm

the answer is d