A) 10 km/h
B) 4 km/h
C) 14 km/h
D) 6 km/h
Correct Answer: A
Solution :
[a] Let speed of the boat in still water be x km/h and Speed of the current be y km/h. Then, upstream speed \[=\left( xy \right)km/h\] and downstream speed \[=\left( x+y \right)km/h\] Now, \[\frac{24}{(x-y)}+\frac{28}{(x+y)}=6\] ? (i) and \[\frac{30}{(x-y)}+\frac{21}{(x+y)}=\frac{31}{2}\] ? (ii) Solving (i) and (ii), we have x = 10 km/h and y = 4 km/hYou need to login to perform this action.
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