Answer: The required value of y is 5.1.
Step-by-step explanation: We are given to find the value of y such that the mean of the following numbers is 7.1 :
5.2, 8.3, 8.5, 7.7, 7.8, y.
We know that
MEAN of a group of numbers is equal to the average of the numbers.
The total number of numbers in the given group = 6
and
the sum of all the numbers in the group
= 5.2 + 8.3 + 8.5 + 7.7 + 7.8 + y
= 37.5 + y.
So, according to the given information, the mean is given by

Thus, the required value of y is 5.1.