Question

The arithmetic mean of a set of 10 numbers is 20. If each number is first multiplied by 2 and then increased by 5, then what is the mean of the new numbers?

(a) 20

(b) 25

(c) 40

(d) 45

Answer 1

Correct option is (d) 45

Mean of 10 number is 20.

Sum of 10 numbers = 200

When each number is multiplied by 2 and 5 is added to each number, new sum = 2 × 200 + 10 × 5 = 450

Now, new mean = \(\frac{450}{10} \) = 45