Question

8.
Out of the three given numbers, the first number is twice the second and thrice the third. If the average of the three numbers is 154. What is the difference between the first and the
third number?
(1) 126
(2) 42
(3) 168
(4) 52
(5) None of these​

Answer 1

Answer:

Option (3)

Step-by-step explanation:

Let the third number be a and second number be 6b.

Given,

      First number is twice of 6b ⇒ first number = 12b

      First number is thrice of a ⇒ first number = 3a

⇒ First number = 12b = 3a

⇒ 12b = 3a

⇒ 4b = a

Now, first number is 12b, second number is 6b and third number is 4b.

Given,

     Average of these numbers is 154.

⇒ ( 12b + 6b + 4b ) / 3 = 154

⇒ 22b = 154 x 3

⇒ b = ( 154 x 3 ) / 22

⇒ b = 21

Hence,

       First number is 12b ⇒ 12( 21 ) ⇒ 252

       Third number is 4b ⇒4( 21 ) = 84

Difference between them ⇒ 252 - 84 ⇒ 168