Question

A train travels at 60km/hr for 0.52hrs. The next 30km/hr for 0.24hrs and next 70km/hr for the speed X. If the average speed is 59.9, find X

Answer 1

average speed = ( total displacement)/total time

total displacement =( 60× 0.52 + 30× 0.24 + 70× X) /( 0.52 + 0.24 + X )

59.9 = ( 31.2 + 7.2 + 70X )/( 0.76 + X)

59.9× 0.76 + 59.9X = 38.4 + 70X

X = 0.7 hrs