# The mean weight of a group of seven boys is 56 kg. The individual weights (in kg) of six of them are 52, 57, 55, 60, 59 and 55. Find the

The mean weight of a group of seven boys is 56 kg. The individual weights (in kg) of six of them are 52, 57, 55, 60, 59 and 55. Find the weight of the seventh boy.​

## This Post Has 4 Comments

1. Expert says:

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240

2. Expert says:

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3. Xavitheking2542 says:

weight of the 7th boy = 54 kg

Step-by-step explanation:

let x be the weight of the 7th boy.

avg. of a gp of 7 boys = 56

(52+57+55+60+59+55+x)/7 = 56

338 + x = 56 * 7

338 + x = 392

x = 392-338

x = 54

4. kayleebug13 says:

Step-by-step explanation:

The mean weight of 7boys is 56

The weight of individuals is 52,57,55,60,59and55

Arranging it in ascending order 52,55,55,x,57,59and 60

Odd no. Mean =n+1/2

7+1/2=4th term =x=56