A car travels from calabar to Enugu, a distance of P km with an average speed of U km per hour and continues to benin, a distance of Q km, with an average speed of Wkm per hour. Find its average speed from Calabar to Benin
A.
(p+q)/(pw + qu)
B.
(uw(p+q))/(pw + qu)
C.
uw(p+q)/pw
D.
uwpw+qu
Correct Answer: (uw(p+q))/(pw + qu)
Explanation
Average speed = totalDistance/TotalTime
from Calabar to Enugu in time t1, hence
t1 = P/U
Also from Enugu to Benin
t2 = q/w
Av. speed = (p + q)/(t1 + t2)
= (p + q)/((p/u) + (q/w))
= p + q x (uw)/(pw + qu)
= (uw(p+q))/(pw + qu)
Average speed = totalDistance/TotalTime
from Calabar to Enugu in time t1, hence
t1 = P/U
Also from Enugu to Benin
t2 = q/w
Av. speed = (p + q)/(t1 + t2)
= (p + q)/((p/u) + (q/w))
= p + q x (uw)/(pw + qu)
= (uw(p+q))/(pw + qu)