If the average of 10 numbers is 625 and the average of 25 numbers is 100, then the average of 35 numbers is equal to_____.

Correct option is D

Given:

Average of 10 numbers = 625

Average of 25 numbers = 100

Formula Used:

​$$Average = \frac{Sum\ of\ observations}{Number\ of\ observations}$$​​

Solution:

Total of 10 numbers = $$10 \times 625$$​ = 6250

Total of 25 numbers = $$25 \times 100$$ = 2500

Total of 35 numbers = 6250 + 2500 = 8750

Average =$$\frac{8750}{35} = 250$$​​