Multiple choice

The ratio of total surface area that of lateral surface area of a cylinder whose radius is $20$cm and height $60$cm, is _________.

  1. $2:1$
  2. $3:2$
  3. $4:3$
  4. $5:3$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total surface area is 2*pi*r*(r+h) and lateral surface area is 2*pi*r*h. The ratio is (r+h)/h = (20+60)/60 = 80/60 = 4/3.

AI explanation

The total surface area of a cylinder is 2*pi*r*(h+r) and the lateral surface area is 2*pi*r*h. Substituting the given values, the total surface area is 2*pi*20*(60+20) = 3200*pi and the lateral surface area is 2*pi*20*60 = 2400*pi. The ratio of total surface area to lateral surface area is 3200*pi : 2400*pi, which simplifies to 4:3.

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