One car moving on a straight road covers one third of the distance with $20 \,km/hr $ and the rest with $60\, km/hr$. The average speed is..........$km/hr$
One car moving on a straight road covers one third of the distance with $20 \,km/hr $ and the rest with $60\, km/hr$. The average speed is..........$km/hr$
$40$
$80$
$46\frac{2}{3}$
$36$
One car moving on a straight road covers one third of the distance with $20 \,km/hr $ and the rest with $60\, km/hr$. The average speed is..........$km/hr$
Average speed $ = \frac{{{\rm{Total\, distance }}}}{{{\rm{Total\, time}}}}$$ = \frac{x}{{{t_1} + {t_2}}}$
$ = \frac{x}{{\frac{{x/3}}{{{v_1}}} + \frac{{2x/3}}{{{v_2}}}}}$$ = \frac{1}{{\frac{1}{{3 \times 20}} + \frac{2}{{3 \times 60}}}} = 36\;km/hr$
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