Out of four numbers, whose average is 60, first one is one-fourth of sum of last three. first number

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4.Average

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Out of four numbers, whose average is $60,$ the first one is one-fourth of the sum of the last three. The first number is

A

$15$

B

$45$

C

$48$

D

$60$

Solution

Let, the number be $x$, then

$x=\frac{240-x}{4}$

$\Rightarrow 4 x=240-x$

$\Rightarrow 4 x+x=240$

$\Rightarrow \quad 2 x=240$

$\Rightarrow x=\frac{240}{5}=48$

Standard 13

Quantitative Aptitude

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