Sun	Mon	Tue	Wed	Thu	Fri	Sat
23	24	25	26	27	28	1
2	3	4	5	6	7	8
9	10	11	12	13	14	15
16	17	18	19	20	21	22
23	24	25	26	27	28	29
30	31	1	2	3	4	5

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Multiple Choice Questions

A boat covers 120 km downstream in x hours and also covers 180 km upstream in x 5 hours If the boat ...........

Quantitative Aptitude(IBPS RRB PO) Boats and Streams

A boat covers 120 km downstream in x hours and also covers 180 km upstream in (x + 5) hours. If the boat covers 350 km in still water in 14 hours, then find the speed of the current?

4 kmph

5 kmph

8 kmph

6 kmph

10 kmph

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Explanation:

Speed of boat in still water = 350/14 = 25 kmph
Speed of downstream = 120/x
Speed of upstream = 180/(x + 5)
((120/x) + 180/(x + 5) = 25 * 2
120x + 600 + 180x = 50 * (x2 + 5x)
30x + 60 = 5x2 + 25x
x² – x – 12 = 0
x²– 4x + 3x – 12 = 0
x(x – 4) + 3(x – 4) = 0
x = 4, -3
Speed of downstream = 120/4 = 30 kmph
Speed of upstream = 180/9 = 20 kmph
Speed of current = (30 – 20)/2 = 5 kmph

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