Question

The average weight of A, B and C is 84 kg. When
D joins this group, the average weight becomes 80
kg. If another man E, Whose weight is 3 kg, more
than that of D replaces A, the average weight of B,
C, D & E becomes 79 kg. Find out the weight of A.​

Answer 1

Step-by-step explanation:

A + B + C = 84 × 3 = 252.....(i)

A + B + C + D = 80 × 4 = 320.....(ii)

On solving equation (i) and (ii)

D = 320 - 252

D = 68

E's weight = 68 + 3 = 71

B + C + D + E = 79 × 4 = 316

B + C + D + 71 = 316

B + C + D = 316 - 71 = 245

Now, from equation (ii)

(A + B + C + D) - (B + C + D)

A = 320 - 245

∴ A = 75 kg

Answer 2

$\mathbb{\bf{\large{\pink{A}\orange{N}\purple{S}\red{W}\blue{E}\pink{R}}}}$

According to the question ,

➣ A + B + C = 84 × 3 = 252 ------(1)

➣ A + B + C + D = 80 × 4 = 320-------(2)

From eqn (1) & (2) ;-

Weight of ,

➣ D = 320 - 252

➣ D = 68

Now,

➣ E's weight = 68 + 3 = 71

And,

➣ B + C + D + E = 79 × 4 = 316

➣B + C + D + 71 = 316

➣ B + C + D = 316 - 71 = 245

Hence, B+C+D =245

Now,

➣ (A + B + C + D) - (B + C + D)

➣A = 320 - 245

➣ ∴   $\boxed{\pink{Weight \: of \:A = 75 kg}}$

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