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SSC CHSL 2021 PYQ — Question 55

SSC CHSL - 19 April 2021 - Shift 3 • Quantitative Aptitude • Q55

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If the diameter of the base of a cone is 18 cm and its curved surface area is 42427cm2424{{2} \over 7}cm^2 , then its height will be:

(Takeπ=227(Take \pi={{22} \over 7}

Show answer & explanation

Correct answer: B

Explanation

The correct answer is Option 2 i.e. 12 cm.

Given that

The diameter of the base of the cone = 18 cm

The curved surface area = 42427cm2424{{2} \over 7}cm^2

Formula used 

The curved surface area of the cone = πr√(r2 + h2) ,  where r = radii & h =hieght of cone

πr√(r2 + h2) = 2970/7

(22/7) * 9 * √(92 + h2) = 2970/7

√(92 + h2) = 15

81 + h2 = 225

h2 = 225 - 81 = 144

h = 12 cm