Question

I need help on 11 plz I need a slot of help

Answer 1

mean = (sum of values) / (number of values)

we know mean is 13 and we are given 8 values. The ninth value is the missing x:

13 = ((sum of 8 values) + x)/9

13 = (12+10+15+12+13+15+11+15+x)/9

13*9 = 103+x

x = 14

The missing value is 14. There are 14 pillows in the last box.