arithmetic questions and answers paper 360 - skillgunNote: Paper virtual numbers may be different from actual paper numbers . In the page numbers section website displaying virtual numbers .
X can row at a speed of 18 kmph in still water.If it takes him thrice as long to row up as to row down the river.Find the rate of stream:
none of the above
Let X’s rate upstream be x kmph.
then ,his rate downstream= 3x kmph.
So, 2x = 18
or x = 9.
Rate upstream=9 km/hr,rate downstream = 27 km/hr.
Hence,rate of stream = 1/2(27-9)km/hr = 9 km/hr.
Peter can row 40 km upstream and 55 km downstream in 13 hours also, he can row 30 km upstream and 44 km downstream in 10 hours.Find the speed of the Peter in still water and the speed of the current:
Let rate upstream = x km/hr
and rate downstream = y km/hr.
Then,40/x +55/y = 13...(i)
and 30/x +44/y = 10
Multiplying (ii) by 4 and (i) by 3 and subtracting ,we get:11/y = 1 or y = 11.
Substituting y = 11 in (i),
we get: x = 5.
Rate in still water =1/2(11+5) kmph = 8 kmph.
Rate of current=1/2(11-5)kmph = 3 kmph
A person can row downstream 10 miles/hr and upstream 7 miles/hr. Find the speed of that person in still water ?
Person's speed in still water = 1/2(10+7)
= 8.5 miles/hr
A man can row 10 kmph in still water and the river is running at 2 kmph. If the man takes 1 hr to row to a place and back, how far is the place?
Man’s rate downstream = (10 + 2) kmph = 12 kmph
Man’s rate upstream = (10 – 2) kmph = 8 kmph
Let the reqd. distance be x km
Then x/12 + x/8 = 1
=> 20x = 96
=> x = 4.8
Hence, the required distance is 4.8 km.
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