Average of three numbers is 28 . If first number is half of second and 3^{rd} number is twice second

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4.Average

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The average of three numbers is $28 .$ If first number is half of the second and the $3^{rd}$ number is twice the second, then the third number is?

A

$48$

B

$36$

C

$24$

D

$18$

Solution

Let the second number $=x$

$\frac{x}{2}+x+2 x=84 \Rightarrow \frac{x+2 x+4 x}{2}=84$

$7 x=84 \times 2 \Rightarrow x=\frac{84 \times 2}{7} \Rightarrow x=24$

Third number $=24 \times 2=48$

Standard 13

Quantitative Aptitude

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