Average of three consecutive odd numbers is 12 more than one-third of first of these numbers. last o

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The average of three consecutive odd numbers is $12$ more than one-third of the first of these numbers. What is the last of the three numbers ?

A

$15$

B

$17$

C

$19$

D

$21$

Solution

Let, the smallest number be $x$, then

$\frac{x}{3}+12=x+2$

$\Rightarrow \frac{x+36}{3}=x+2$

$\Rightarrow x+36=3(x+2)$

$\Rightarrow x+36=3 x+6$

$\Rightarrow 3 x-x=36-6$

$\Rightarrow 2 x=30$

$\Rightarrow x=15$

Hence, the third number $=15+4=19$.

Standard 13

Quantitative Aptitude

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