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PT. Usha runs around a circular path of area 754600 sqmetre. How long will she take to run 20 rounds at the speedof 16 km/hr. |
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Answer» given area pi r^2 = 754600 m^2==> r^2 = 754600 * 7/22 = 68600 * 7/2 = 34300 * 7 = 7^2 * 7^2 *10^2So r = 490 mCircumference of that circular track = 2 pi r = 2 * 22/7 * 490 = 22 * 140 mSo for 20 rounds the distance covered = 20 * 22 * 140mTime taken to go for 20 rounds = distance / speedt = 20 * 22 * 140 / (16 * 5/18) [here km p h is changed into m/s]So time taken = 200 * 22 * 14 * 18 / 80 = 13860 sOr 13860/60 min= 231 min =3 hour 51 minute |
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