supriya runs a marathon race in 50 minutes at an average speed of 48 km/hr in order to set a national record she need to win the race in 40 minutes considering that her speed remain constant at what minimum speed she run to set the record
a) 70 km/hr
b) 60 km/hr
c) 55 km/hr
d) 50km/hr

• d = 48 * 50/60 = 40 km
  
  s = 40km / 40 min = 60 km/h
• 9 years agoHelpfull: Yes(22) No(1)
• speed1=48km/hr and time1=50/60hr
  distance=speed*time
  distance=48*50/60=40km
  now it is given that the distance remains same but she has to win the race in 40 min
  therefore now:
  time2=40/60 hr and distance=40km
  speed2=40/(40/60)=40*60/40=60 km/hr
  ans: (b) 60km/hr
• 8 years agoHelpfull: Yes(5) No(0)
• b:) 60km/hr
• 9 years agoHelpfull: Yes(2) No(0)
• 50mins=5/6hr
  distance=48*(5/6)=40km
  40mins=2/3hr
  speed=40/(2/3)=40*(3/2)=60km/hr.
• 8 years agoHelpfull: Yes(2) No(0)
• b) 50*48=40*x
  x=60
  
• 8 years agoHelpfull: Yes(2) No(0)
• as we know speed*time=distance
  40km*(50/60)=distance
  therefore D=40km
  now the time is reduced to 40mints,we have to find the speed
  S=D/T
  S=40km/(40/60)
  therefore Speed S=60KMPH
  
• 8 years agoHelpfull: Yes(2) No(0)
• (b) (50*48)/40
• 7 years agoHelpfull: Yes(0) No(1)
• Given,s1=48,s2=?,t1=50,t2=40
  speed is inversely proportional to time---->1
  t1:t2=50:40
  t1/t2=5:4
  s1:s2=4:5(from 1)
  so,4 : 5
  |*12 |*12
  48 60
  4 is multiplied with 12 inorder to get 48,
  s2 can be obtained by multilying 5 with 12
  Answer:5*12=60(b)
• 4 years agoHelpfull: Yes(0) No(0)