Question

The arithmetic mean of the cubes of first four natural numbers is

• A. $24$
• B. $25$
• C. $28$
• D. $30$

Answer 1

The correct option is B $25$

The first four natural numbers are 1,2,3,4

$A.M=\frac{\sum x}{n}=\frac{1^3+2^3+3^3+4^3}{4}$

$\Rightarrow \frac{1+4+27+64}{4}=\frac{100}{4}=25$