Find values of x

Question

The mean of a set of data 4,x+1,7,4 and (x²-1) is 9. Find the possible values of x

Answer 1

The mean is the sum of values divided by their count: ( 4 + x+1 +7 + 4 + x² - 1 )/5 = 9.

This means: x + x² = 30 which implies x= 5 or x=-6.