4. Three years ago, the average age of A, B and C was 27 years and that of Band C 5 years ago was
20 years. A's present age is
(a) 30 years
(b) 35 years
(C) 40 years
(d) 48 years
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4. Three years ago, the average age of A, B and C was 27 years and that of Band C 5 years ago was
20 years. A's present age is
(a) 30 years
(b) 35 years
(C) 40 years
(d) 48 years
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Let's consider the present age of A to be ⇒ x
Let's consider the present age of B to be ⇒ y
Let's consider the present age of C to be ⇒ z
Age of A, B and C, 3 years ago would be ⇒
Age of A, 3 years would be ⇒ x-3
Age of B, 3 years would be ⇒ y-3
Age of C, 3 years would be ⇒ z-3
Average age of A, B and C, three years ago ⇒ 27
Formula for average ⇒
Therefore we must simplify this equation ⇒
⇒ (1)
Ages of A, B and C, 5 years ago would have been ⇒
Age of B, 3 years would be ⇒ y-5
Age of C, 3 years would be ⇒ z-5
Average age of B and C, five years ago ⇒ 20
Formula for average ⇒
Therefore we must simplify this equation ⇒
⇒ (2)
From (1) and (2) we must subtract them to find the A's present age.
90 - 50 = 40
∴ The present age of A is (c) 40 years
Verified answer
Answer:
present age of B is 25
present age of C is 25
so
average age of A, B and C in present is
A+B+C/3=27+3
A+25+25/3=30
A+50/3=30
A+50=90
A=90-50
A=40
A's present age is 40