﻿ The length of a hall is 20 m and width 16 m. The sum of the areas of the floor and the flat roof is equal to the sum of the areas of the four walls. Find the height of the hall. from Mathematics Surface Areas and Volumes Class 9 CBSE
The length of a hall is 20 m and width 16 m. The sum of the areas of the floor and the flat roof is equal to the sum of the areas of the four walls. Find the height of the hall.

Let the height of the hall be h m.
Area of the floor = l x b
= 20 x 16 = 320 m2 Area of the flat roof = l x b
= 20 x 16 = 320 m2 Sum of the areas of the four walls = 2(l + b) h
= 2(20 + 16) h = 72 h m2 According to the question,
72 h = 320 + 320

Hence, the height of the hall is

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(i)

 xi 10 15 20 25 30 35 40 Total fi 4 6 8 18 6 5 3 50

(ii)

 xi 12 13 14 15 16 17 18 Total fi 1 3 4 8 10 3 1 30

(iii)

 xi 50 75 100 125 150 175 200 Total fi 12 18 50 70 25 15 10 200

(i)

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(iii)

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A.

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B.

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