Question

from a point on a circular track 120 km long A,B and C started running in the same direction at the same time speed of 21 , 63 and 66km/per hour respectively then on starting point all three will meet again after ?​

Answer 1

Given:

Distance = 120 km

Speed of A = 21 km/h

Speed of B = 63 km/h

Speed of C = 66 km/h

To FInd:

The time they will meet again

Solution

Find the time A will take to cover 1 round:

Time = Distance ÷ Speed

Time = 120 ÷ 21

Time = 40/7 hour

Find the time B will take to cover 1 round:

Time = Distance ÷ Speed

Time = 120 ÷ 63

Time = 40/21 hour

Find the time C will take to cover 1 round:

Time = Distance ÷ Speed

Time = 120 ÷ 66

Time = 20/11 hour

Find the required time for them to meet :

Required time = (LCM of the numerator) ÷ (HFC of denominator)

Required time = (LCM of 40 , 40, 20) ÷ (HFC of 7, 21, 11)

Required time = 40 ÷ 1

Required time = 40 hours

Answer: They will meet after 40 hours.

Answer 2

$\huge{\boxed{\overline{\underline{\mathfrak{\fcolorbox{cyan}{blue}{Answer}}}}}}$

$\implies$ 40 hours.

$\large\underline\mathrm{Given:-}$

Distance = 120km

speed of A = 21 km/h

speed of B = 63 km/h

speed of C = 66 km/h

$\large\underline\mathrm{Solution}$

Find the time A.

Distance = Time/speed

$\implies$ 120/21

$\implies$ 40/7 hours.

Find the time B.

Distance = Time/speed

$\implies$ 120/63

$\implies$ 40/21 hours.

fine the required time for them to meet.

Required time = L.C.M 40, 40, 20 / H.C.F 7, 21, 11

Required time = 40 hours.

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