RRB Junior Engineer Stage 1 Model Papers 3

Question : 17 of 100

Marks: +1, -0

Of the three numbers, the first is twice the second, and the second is twice the third. The average of the reciprocal of the numbers is 7/12. The numbers are:

20, 10, 5
4, 2, 1
36, 18, 9
16, 8, 4

Validate

Solution:

Let third number = x
then,
second number = 2x
first number = 4 x
According to question

{(1/x+1/{2x}+1/{4x})}/3=7/12

∴ x = 9
∴ first number

= 4x = 4 × 9 = 36

second number

= 2x = 2 × 9 = 18

third number

= x = 9

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