Question:A man can row three quarters of a kilometre against the stream in `11 1/4` minutes and returns in `7 1/2` minutes. The speed of the man is still water is :
A `2 km∕hr`
B `3 km∕hr`
C `4 km∕hr`
D `5 km∕hr`
/14
+ Answer
D
+ ExplanationSpeed upstream
`= (3/4 xx 4/45 xx 60) kmph`
`= 4 kmph.`
Speed downstream
`= (3/4 xx 2/15 xx 60) kmph`
`= 6 kmph.`
Speed in still water
`= 1/2 (6 + 4) kmph`
`= 5 kmph`