A boat goes 8 km upstream in 24 minutes. The speed of stream is 4 km/hr. The speed of boat in still water is:

A. 25 km/hr

B. 26 km/hr

C. 22 km/hr

D. 24 km/hr

• each machine got 2hrs to complete work,so for 100% actual speed time is 2 hrs then..taking 25% in that the work complete for half an hour...so,there are two machines so one hour....(reduced)...then the ans will be
  9 hrs
• 9 years agoHelpfull: Yes(27) No(8)
• rate upstream =8/24*60=20kmph
  speed of stream=4kmph
  let speed of boat in still water=xkmph
  speed upstream=x-4kmph
  x-4=20
  x=24kmph
• 9 years agoHelpfull: Yes(25) No(0)
• 2 of m/c speed increased 25% so now it is 2.50
  tot=3+2.50=5.50
  let x hour will take to complete the work
  5*10=5.50*x
  x=9 1/11 will take to complete the same work
• 9 years agoHelpfull: Yes(13) No(8)
• speed increased by 25% means time decreased by 20%
  Each machine take 2 hrs. so 2 machines time decreased by=3.2 hr rest of the three take 6 hr
  Total time=3*2+2*(2*80/100)=9.2
• 9 years agoHelpfull: Yes(8) No(9)
• boatstream=?,,, currentstream=4km/hr
  upstream=boatstream-currentstream
  upstream=distance/time=(8*60)/24=20km/hr
  20=boatstream-4
  boatstream=20+4=24
• 9 years agoHelpfull: Yes(6) No(0)
• what is the correct answer?
  
• 9 years agoHelpfull: Yes(4) No(0)
• each ordinary machine takes 2 hours.
  ratio of time consumption between single ordinary machine and single improvised machine
  125:100 = 2:x
  so now one improved machine will take 1.6 hours instead of 2 hours. 2 machine will take 3.2 hours.
  total time consumption is (3*2)+3.2= 9.2 hours.
• 9 years agoHelpfull: Yes(1) No(3)
• 33. A boat goes 8 km upstream in 24 minutes. The speed of stream is 4 km/hr. The speed of boat in still water is:
  A. 25 km/hr B. 26 km/hr
  C. 22 km/hr D. 24 km/hr
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  answer with explanation
  Answer: Option D
  
  Explanation:
  
  Speed upstream @@=dfrac{8}{left(dfrac{24}{60}right)}@@ = 20 km/hr
  
  Speed of the stream = 4 km/hr
  
  speed of boat in still water = (20+4) = 24 km/hr
• 7 years agoHelpfull: Yes(1) No(0)
• Su=x-y,where x is the speed of boat in still water, y is the speed of stream and Su is boat upstream speed so,
  Su=8/24/60=20km/hr
  Now,
  20=x-4
  X=24km/hr
• 7 years agoHelpfull: Yes(1) No(0)
• 9.2 hours
  
• 9 years agoHelpfull: Yes(0) No(4)
• I think 9 z correct ans
  
• 9 years agoHelpfull: Yes(0) No(3)
• D = 8km
  T = 24min (i.e) 24/60hr
  speed in upstream is " a-b=speed "
  where a is the speed of the boat and b is the speed of the stream
  so we have the value of b i.e speed of the stream
  and we have the value of distance and time of the boat, we can find the speed i.e a-b = speed
  by substitute the value of b and speed we get the value of a which was the speed of the boat in the still water.
  hence we get the above equation as :
  a-b=speed
  a-4=20 // speed = distance/time 8*60/24=20
  a=24
  hence the speed of the boat is 24km/hr.
• 6 years agoHelpfull: Yes(0) No(0)