A) 37.5 km/h
B) 36 km/h
C) 48 km/h
D) 30 km/h
Correct Answer: B
Solution :
Distance covered in (12 min + 8 min) \[=\left[ 30\times \frac{12}{60}+45\times \frac{8}{60} \right]\]km =12 km Total distance = 12 km, Total time = 20 min \[=\frac{20}{60}\,\,h=\frac{1}{3}\,\,h\] Average speed \[=\frac{12}{\frac{1}{3}}\] km/h = 36 km/h Short Trick\[\frac{2xy}{x+y}=\frac{2\times 30\times 45}{75}=36\]You need to login to perform this action.
You will be redirected in
3 sec