A plane left 30 minute late than its schedule time and in order to reach the destination 1500. away in time It had to increase its speed by 100km/h. from the usual speed. find its usual speed?
Beajeshpandey:
1500 km
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Ab iss ka koi faayada nhi ppr will be reconducted..
fir v i want its ans becoz this is not in the book
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Let the usual speed of plane be 'S' km/hr
Usual time = T
It left 30 minutes late than usual:
Hence at normal speed, it would have reached half hour late:
1500/S = T + 30 mins = T + 1/2 hrs.....(i)
S = S + 100, reached on time
1500/S + 100 = T....(ii)
(i) - (ii)
1500/S - 1500/S+100 = 1/2
1500*(1/S - 1/S+100) = 1/2
1500*2*(S+100-S/(S*(S+100))) = 1
1500*2*100 = S*(S+100)
50*30*10*10*2 = S*(S+100)
50*10* 30*10*2 = S*(S+100)
500 * 600 = S*(S+100)
Comparing S = 500, then S+100 = 600
Hence, S = 500 km/hr
Usual speed = 500 km/hr
Hope it helps.
Usual time = T
It left 30 minutes late than usual:
Hence at normal speed, it would have reached half hour late:
1500/S = T + 30 mins = T + 1/2 hrs.....(i)
S = S + 100, reached on time
1500/S + 100 = T....(ii)
(i) - (ii)
1500/S - 1500/S+100 = 1/2
1500*(1/S - 1/S+100) = 1/2
1500*2*(S+100-S/(S*(S+100))) = 1
1500*2*100 = S*(S+100)
50*30*10*10*2 = S*(S+100)
50*10* 30*10*2 = S*(S+100)
500 * 600 = S*(S+100)
Comparing S = 500, then S+100 = 600
Hence, S = 500 km/hr
Usual speed = 500 km/hr
Hope it helps.
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