A circular disc of area 49π sq. meters rolls down an incline of 88 km length. What is the number of revolution it makes during this journey?
i) Area of the circle = πr² = 49π m²; solving r = 7 m.

ii) So circumference of the circular disc = 2πr = 14π = 44m [Taking π = 22/7]

iii) So number of revolutions = total length traveled/circumference = (88*1000)/44 = 2000
[One km = 1000m; so 88km = 88*1000 m]
but in my anwer key the ans is 200 and other options are 150,250,280&300

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  1. π = 22/7 UGH. Don't ever use that.

    You did it correctly, your answer key is wrong.

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