Boats and Streams - Wikitechy https://www.wikitechy.com/interview-questions/category/boats-and-streams/ Interview Questions Mon, 20 Sep 2021 10:17:59 +0000 en-US hourly 1 https://wordpress.org/?v=6.9 https://www.wikitechy.com/interview-questions/wp-content/uploads/2025/10/cropped-wikitechy-icon-32x32.png Boats and Streams - Wikitechy https://www.wikitechy.com/interview-questions/category/boats-and-streams/ 32 32 A man rows a boat at a speed of 15 mph in still water. Find the speed of the river if it takes her 4 hours 30 minutes to row a boat to a place 30 miles away and return https://www.wikitechy.com/interview-questions/boats-and-streams/a-man-rows-a-boat-at-a-speed-of-15-mph-in-still-water-find-the-speed-of-the-river-if-it-takes-her-4-hours-30-minutes-to-row-a-boat-to-a-place-30-miles-away-and-return/ https://www.wikitechy.com/interview-questions/boats-and-streams/a-man-rows-a-boat-at-a-speed-of-15-mph-in-still-water-find-the-speed-of-the-river-if-it-takes-her-4-hours-30-minutes-to-row-a-boat-to-a-place-30-miles-away-and-return/#respond Wed, 18 Aug 2021 02:46:12 +0000 https://www.wikitechy.com/interview-questions/?p=2079

A man rows a boat at a speed of 15 mph in still water. Find the speed of the river if it takes her 4 hours 30 minutes to row a boat to a place 30 miles away and return.

A. 5 mph

B. 10 mph

C. 12 mph

D. 20 mph

Answer : A. 5 mph

Explanation:

Let us assume that the speed of the river = x mph
Speed of boat on outward journey = (15 – x) mph (Assuming the outward journey is upwards)
Speed on boat on return journey = (15 + x) mph (Assuming the return journey is downwards)
Time = Distance/Speed
4 hours 30 minutes = 4.5 hours
Total time taken = 30 / (15 – x) + 30 / (15 + x) = 4.5
30(15 + x) + 30(15 – x) / (15 – x) (15 + x) = 4.5
450 + 30x + 450 – 30x = 4.5 (225 – x2)
900 = 4.5 (225 – x2)
200 = 225 – x2
x2 = 25
x = 5
The speed of river is 5mph.

]]> https://www.wikitechy.com/interview-questions/boats-and-streams/a-man-rows-a-boat-at-a-speed-of-15-mph-in-still-water-find-the-speed-of-the-river-if-it-takes-her-4-hours-30-minutes-to-row-a-boat-to-a-place-30-miles-away-and-return/feed/ 0 A boat covers a distance of 30 km downstream in 2 hours while it takes 6 hours to cover the same distance upstream. What is the speed of the boat in km/hr ? https://www.wikitechy.com/interview-questions/boats-and-streams/a-boat-covers-a-distance-of-30-km-downstream-in-2-hours-while-it-takes-6-hours-to-cover-the-same-distance-upstream-what-is-the-speed-of-the-boat-in-km-hr/ https://www.wikitechy.com/interview-questions/boats-and-streams/a-boat-covers-a-distance-of-30-km-downstream-in-2-hours-while-it-takes-6-hours-to-cover-the-same-distance-upstream-what-is-the-speed-of-the-boat-in-km-hr/#respond Wed, 18 Aug 2021 02:44:04 +0000 https://www.wikitechy.com/interview-questions/?p=2078

A boat covers a distance of 30 km downstream in 2 hours while it takes 6 hours to cover the same distance upstream. What is the speed of the boat in km/hr ?

A. 5

B. 7.5

C. 10

D. 12

Answer : C. 10

Explanation :

  • Speed of boat downstream
    = Distance covered / Time taken
    = 30/2
    = 15 km/h
  • Now, speed of boat upstream
    = Distance covered / Time taken
    = 30/6
    = 5 km/h
  • Now, speed of boat = (Speed downstream + Speed upstream)/2
    = (15 + 5)/2
    = 20/2
    = 10 km/h.
]]> https://www.wikitechy.com/interview-questions/boats-and-streams/a-boat-covers-a-distance-of-30-km-downstream-in-2-hours-while-it-takes-6-hours-to-cover-the-same-distance-upstream-what-is-the-speed-of-the-boat-in-km-hr/feed/ 0 A motorboat whose speed is 15 km/hr in still water goes 30km downstream and comes back in four and a half hours. The speed of the stream is ? https://www.wikitechy.com/interview-questions/boats-and-streams/a-motorboat-whose-speed-is-15-km-hr-in-still-water-goes-30km-downstream-and-comes-back-in-four-and-a-half-hours-the-speed-of-the-stream-is/ https://www.wikitechy.com/interview-questions/boats-and-streams/a-motorboat-whose-speed-is-15-km-hr-in-still-water-goes-30km-downstream-and-comes-back-in-four-and-a-half-hours-the-speed-of-the-stream-is/#respond Wed, 18 Aug 2021 02:39:49 +0000 https://www.wikitechy.com/interview-questions/?p=2075

A motorboat whose speed is 15 km/hr in still water goes 30km downstream and comes back in four and a half hours. The speed of the stream is ?

A. 4.5 km/hr

B. 6 km/hr

C. 7 km/hr

D. 5 km/hr

Answer : D. 5 km/hr

Explanation :

Let the speed of the stream be x km/hr. Then,
Speed downstream = (15 + x) km/hr
Speed upstream = (15 – x) km/hr

We know from question that it took 4(1/2)hrs to travel back to same point.
So, (30/15 + x) + (30/15 − x) = 4(1/2)
=> 900/225 − x2 = 9/2
=> 9x2 = 225
=> x = 5km/hr.

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