The average weight of P, Q and R is 60kgs. Weight of Q is 20 kgs less than P’s weight and 5kgs more than R’s weight. What will be the average P, Q, R and S, if S weighs 2 kgs more than R ?

\$"Average" = "sum of set of numbers" / "amount of numbers in set"\$

Average weight of P, Q and R = 60kgs

⇒ \$(P + Q + R)/3 = 60\$

⇒ \$P + Q + R = 60 \times 3 = 180\$ → (1)

Let "x" be the weight

According to the problem,

⇒ P = x, Q = x - 20, R = x - 25 → (2)

Substitute the values in equation(1)

⇒ \$x + x - 20 + x - 25 = 180\$

⇒ \$3x= 180 + 45 = 225\$

⇒ \$x= 225/3 = 75\$

Substituting x in equation(2)

P = 75, Q = 55, R = 50

Since S is 2 more than R then S = 52

The average P, Q, R and S = \$(75 + 55 + 50 + 52)/4\$ = \$232/4 = 58\$ Hence, the average weight P, Q, R and S is 58 kgs