(solved)Question 9 SSC-CGL 2020 March 3 Shift 2

Average of first four numbers is 3 times the fifth number. The average of all five numbers is 85.8. What is the fifth number?

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Question 9SSC-CGL 2020 Mar 3 Shift 2

Average of first four numbers is 3 times the fifth number. The average of all five numbers is 85.8. What is the fifth number?

Solution in Detail

Fifth number = $\displaystyle x$

Given average of first four = $\displaystyle 3x$

$\displaystyle \therefore$ sum of first four = $\displaystyle 4 \times 3x = 12x$

$\displaystyle \therefore$ sum of all five $\displaystyle = 12x + x = 13x$

Average of all five given $\displaystyle 85.8$

$\displaystyle \therefore \frac{13x}{5} = 85.8$

$\displaystyle \implies x = 33\:\underline{Ans}$