A car travels from calabar to Enugu a distance ... - JAMB Mathematics 1991 Question
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
\(\frac{(p + q)}{pw + qu}\)
B
\(\frac{uw(p + q)}{pw + qu}\)
C
\(\frac{uw(p + q)}{pw}\)
D
\(\frac{uw}{pw + qu}\)
correct option: b
Average speed = \(\frac{\text{total Distance}}{\text{Total Time}\)
from Calabar to Enugu in time t1, hence
t1 = \(\frac{P}{U}\) also from Enugu to Benin
t2 \(\frac{q}{w}\)
Av. speed = \(\frac{p + q}{t_1 + t_2}
= \(\frac{p + q}{\frac{p}{u} + \frac{q}{w}\)
= p + q x \(\frac{uw}{pw + qu}\)
= \(\frac{uw(p + q)}{pw + qu}\)
from Calabar to Enugu in time t1, hence
t1 = \(\frac{P}{U}\) also from Enugu to Benin
t2 \(\frac{q}{w}\)
Av. speed = \(\frac{p + q}{t_1 + t_2}
= \(\frac{p + q}{\frac{p}{u} + \frac{q}{w}\)
= p + q x \(\frac{uw}{pw + qu}\)
= \(\frac{uw(p + q)}{pw + qu}\)
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