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SSC CHSL 2021 PYQ — Question 55

SSC CHSL - 6 Aug 2021 - Shift 3 • Quantitative Aptitude • Q55

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The circumference of a circle is 'a' units and the area of the circle is 'b' square units. If a : b is equal to 4 : 5, then the radius of the circle is:

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Correct answer: A

Explanation

The correct answer is option 1 i.e. 2.5 cm

Explanation:

According to the given question,

a = 2πr2 \pi r and b = πr2\pi r^2

Now, 2πr2 \pi r : πr2\pi r^2 = 4 : 5

⇒ 2r=45{2 \over r} = { 4 \over 5}

⇒ r = 2.5

Hence the required answer is 2.5 cm.