Question

There are four numbers p, q, r and s. Average of p, q and r is 71 and average of q, r and s is 52. If p is 72 and r is 81. Find the sum of p and s.
1. 65
2. 87
3. 78
4. 56

Answer 1

Correct Answer - Option 2 : 87

Given

The average of p, q and r is 71

The average of q, r and s is 52

P = 72 , r = 81

Formula used

Average = Sum of all observations/ Number of observations

Calculation

(p + q + r)/3 = 71

⇒ p + q + r = 213

⇒ 72 + q + 81 = 213

⇒ q + 153 = 213 

⇒ q = 213 - 153

⇒ q = 60

(q + r + s)/3 = 52

⇒ q + r + s = 156

⇒ 60 + 81 + s = 156

⇒ s = 156 - 81 - 60

⇒ s = 15

so, p + s = 72 + 15

⇒ 87

∴ The value of (p + s) is 87.