SSC MTS 2021 Question Paper Shift 1 (Nov 2nd)

Question 64

The average of three numbers is 45. The first number is thrice the second, and the second number is twice the third. Find the difference between the first number and the second number.

Solution

According to the given condition :

Let the third number be x. 

  • Second number is twice of third. (given)

So, Second number will be 2x.

  • First number is thrice of second. (given)

So, Third number will be 6x. 

As we know, 

$$Average\ =\ \frac{sum\ of\ observation}{Number\ of\ observation}$$

$$\therefore\ 45\ =\ \frac{x+2x+6x}{3}$$
$$\therefore\ 135\ =\ 9x$$
x = 15
So, The difference between the first and second number is : 
i.e; 6x - 2x = 4x 
i.e; $$4\times\ 15=60$$
Hence, Option C is correct

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