CAT Exam Model Paper 5 with solutions for free online practice

Question : 16 of 60

Marks: +1, -0

On 1 st January, 2000 the average age of a family of 6 people was 'A' years. After 5 years a child was born in the family and one year after that the average age was again found to be 'A' years. What is the value of ‘A’? (Assume that there are no other deaths and births.)

Validate

Solution:

Total age of the 6 people on 1 st January 2000 = 6A
Total sum of ages (including child's) of the family after 5 years = 6(A + 5) = 6A + 30
Total sum of ages (including child’s) of the family after 6 years = 6A + 30 + 7 = 6A + 37
Average

= { ( 6 {\A } + 37 ) }/ { 7 } = { \A }

Hence, 7A = 6A + 37 or A = 37.

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