Question

The average of two numbers A and B is 20, that of B and C is 19 and C and A is 21. What is the value of A?

• A. 24
• B. 22
• C. 20
• D. 18

Answer 1

Answer:

B. 22

Solution: Given: The average of two numbers A and B is 20, that of B and C is 19 and C and A is 21. Concept Used: Average = Sum of Observation/Tota number of Observation Calculation: Average of two number A and B is 20 Sum of two number = 20 × 2 = 40 ---- 1 Average of two number B and C is 19 Sum of two number = 19 × 2 = 38 ---- 2 Average of two number C and A is 21 Sum of two number = 21 × 2 = 42 ---- 3 Add equation 1, 2 and 3 ⇒ 2(A + B + C) = 40 + 38 + 42 ⇒ A + B + C = 60 ---- 4 According to the question, The Value of A Subtract equation 2 from equation 4 ⇒ A = 60 - 38 ⇒ 22 ∴ The value of A is 22.