. On a river, Q is the midpoint between two points
P and R on the same bank of the river. A boat
can go from P to Q and back in 12 hours, and go
from P to Rin 16 hours 40 min. How long would
it take to go from R to P ?
Answers
The speed of a boat still water with current speed, And the distance between P and R
Time required travelled from P to R = 16 H 40 M
PQ = QR (Q is midpoint)
Required time to travell PQ
1/2(16H,40M)=8H,20Min
Total required time from PtoQ+QtoP=12H
= 8H20M+Q to P=12H
time Q to P = 12H−8H20M
= 3H40 M
=2[3H40M]
=7H 20 Minutes
=7 1/3 hr s.
Answer:
Step-by-step explanation:
Let say distance between P Q = D
then PR = 2D ( as Q is mid point of PR)
Boat goes from P to Q & come back Q to P in 12 Hrs
Speed of Boat = B km/Hr
Speed of Stream = S Km/Hr
D/(B+S) + D/(B-S) = 12
Multiplying by 2
2D/(B+S) + 2D/(B-S) = 24
out of these two time one is time from P to R & another is time from P to R
P to R = 16 hr 40 mins = 50/3 hrs
=> 50/3 + time from R to P = 24
=> Time from R to P = 24 - 50/3
=> Time from R to P = 22/3 Hrs