2 Views

Question : The average age of A and B is 20 years. If A is to be replaced by C, the average would be 19 years. The average age of C and A is 21 years. The ages of A, B, and C in order (in years) are:

Option 1: 18, 22, and 20

Option 2: 18, 20, and 22

Option 3: 22, 18, and 20

Option 4: 22, 20, and 18


Team Careers360 7th Jan, 2024
Answer (1)
Team Careers360 18th Jan, 2024

Correct Answer: 22, 18, and 20


Solution : Given: The average age of A and B = 20 years
If A is to be replaced by C, the average would be 19 years.
The average age of C and A = 21 years
So, $\frac{A+B}{2}$ = 20
⇒ A + B = 40 years ------(1)
$\frac{A+C}{2}$ = 21
⇒ A + C = 42 years ------(2)
If A is replaced by C, then,
$\frac{B + C}{2}$ = 19
⇒ B + C = 38 years ------(3)
Add equation (1), (2) and (3)
(A + B) + (A + C) + (B + C) = 40 + 42 + 38
⇒ A + B + C = 60 -------(4)
Subtract equation (1) from (4)
(A + B + C) – (A + B) = 60 – 40
⇒ C = 20 years
Subtract equation (2) from (4)
(A + B + C) – (A + C) = 60 – 42
⇒ B = 18 years
Subtract equation (3) from (4)
(A + B + C) – (B + C) = 60 – 38
⇒ A = 22 years
Hence, the correct answer is 22, 18, and 20.

How to crack SSC CHSL

Candidates can download this e-book to give a boost to thier preparation.

Download Now

Know More About

Related Questions

TOEFL ® Registrations 2024
Apply
Accepted by more than 11,000 universities in over 150 countries worldwide
Manipal Online M.Com Admissions
Apply
Apply for Online M.Com from Manipal University
View All Application Forms

Download the Careers360 App on your Android phone

Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile

150M+ Students
30,000+ Colleges
500+ Exams
1500+ E-books