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A 5 m 60 cm high vertical pole casts a shadow 3 m 20 cm long. Find at the same time the height of a pole which casts a shadow 5 m long.

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Question

A 5 m 60 cm high vertical pole casts a shadow 3 m 20 cm long. Find at the same time the height of a pole which casts a shadow 5 m long.

Sum
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Solution

Given,

length of shadow of 5 m 60 cm high vertical pole = 3 m 20 cm

We know that 5 m 60 cm = 5 × 100 + 60

= 500 + 60

= 560 cm

3 m 20 cm = 3 × 100 + 20

= 300 + 20

= 320 cm

Length of shadow of second pillar = 5 m

= 5 × 100

= 500 cm

Let the length of the pillar = y

ratio of both

Then `560/320 = y/500`

on multiplying thunderbolts

`320 × y = (560×500)/30`

`y = (560×500)/320`

y = 875

Hence, length of shadow of the pillar = 875 cm

= 8 m 75 cm

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Chapter 11: Direct and Inverse Proportions - EXERCISE 11.1 [Page 136]

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NCERT Mathematics [English] Class 8
Chapter 11 Direct and Inverse Proportions
EXERCISE 11.1 | Q 9. (ii) | Page 136

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