1.

The average weight of a group of 3 people A, B and C is 70 kg. When D joins this group, the average becomes 60 kg, One man E, whose weight is 5 kg more than that of D, replaces A and the average weight of B, C, D, and E now becomes 59 kg. A's weight (in kg) is:1. 402. 503. 594. 39

Answer» Correct Answer - Option 4 : 39

Given:

Average weight of A, B, and C = 70 kg

Average weight of A, B, C, and D = 60 kg

Weight of E = Weight of D + 5 kg

Average weight of B, C, D and E = 59 kg

Concept used:

Sum of weight = Average × Number of observation

Calculation:

A + B + C = 70 × 3

⇒ A + B + C = 210 kg               .............(1)

A + B + C + D = 60 × 4

⇒ A + B + C + D = 240 kg        .............(2)

B + C + D + E = 59 × 4

⇒ B + C + D + E = 236 kg         ............ (3)

Subtracrt (1) in (2),

(A + B + C + D) – (A + B + C) = 240 – 210

⇒ D = 30 kg

Weight of E = Weight of D + 5 kg

⇒ E = 30 + 5

⇒ E = 35 kg

B + C + D + E = 236                 [Using eqn (3)]

⇒ B + C + 30 + 35 = 236

⇒ B + C = 236 – 65

⇒ B + C = 171 kg                ------------(4)

Subtract (4) in (1)

(A + B + C) – (B + C) = 210 – 171

⇒ A = 39 kg

∴ The weight of A is 39 kg.


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