Answer: Option D Explanation:4/5 of speed = 5/4 of original time
5/4 of original time = original time + 60 minutes
1/4 of original time = 60 minutes
Thus, original time = 60*4 = 240 minutes = 240+60 = 300 minutes
Answer: Option B Explanation:Let man's rate upstream be X km/ph.Then his rate downstream = 2x km/ph
Speed in still water : Speed of stream = (2x + x /2): 2x-x/2) = 3x/2:x/2 = 3:1
Answer: Option C Explanation:Let the man's rate upstream be x km/ph and that downstream be y km/ph.Then distance covered upstream in 8 hrs 48 mins= Distance covered downstream in 4 hours => (x*8 4/5) = (y*4) => 44/5x = 4y => y=11/5 x
Required ratio = (y+x/2): (y-x/2) = (16x/5*1/2): (6x/5*1/2) = 8/5:3/5 = 8:3
Answer: Option C Explanation:Speed in still water = 1/2 (11+5) km/ph = 8km/ph
Answer: Option C Explanation:Let speed upstream be x km/hr.then, speed downstream = 3x km/hr.
speed in still water = 1/2 (3x+x) km/hr = 2x km/hr.
Therefore 2x =28/3 => x= 14/3.
so, speed upstream = 14/3 km/hr ; speed downstream =14 km/hr
Hence, speed of the current = 1/2 (14- 14/3) km/hr = 14/3 km/hr =4 2/3 km/hr.