A well of diameter 150 cm has a stone parapet around it. If the length of the outer edge of the parapet is $660 cm$ , then find the width of the parapet.

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20 cm

30 cm

40 cm

50 cm

answer is B.

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Detailed Solution

Given a well of diameter 150 cm has a stone parapet around it having length of the outer edge is 660 cm.
Assume, width of the parapet = w.
The radius of the well is half of it’s diameter,

⇒ r = 1502 ⇒ r = 75 c m

According to the question,
Circumference of outer edge of well = 660 cm.

2 π r = 660 ⇒ 2 × 227 × w + 75 = 660 ⇒ w + 75 = 660 × 7 22 × 2 ⇒ w + 75 = 105 ⇒ w = 105 − 75 w = 30 c m

Therefore, the width is 30 cm.
Hence, option 2 is correct.

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