What was the average number of items purchased by the last 15 customers only?

Question

In a supermarket, the first 25 customers of the day purchased an average of two items each.

After a further 15 customers, the average number of items purchased by each customer rose to eight.

What was the average number of items purchased by the last 15 customers only?

Answer 1

Average will be 18
Let Total no. of items purchase by 25 customers be x
Total no. of items purchase by 15 customers be y
(x / 25)=2
so
x = 50

now
(x+y)/40= 8
y= 270
so average of y will be y/15=270/15= 18

Comments

Wonderful :)