Ramu starts from P towards Q at a speed of 30 kmph and after every 12 min increase his speed by 5 kmph. If the distance between P and Q is 52 km, then how much time does he take to cover the distance?
30*12/60 +35*12/60....N times=52
1/5(30+35....N)=52
This has become an A.P with a d=5
sn=n/2(2a+(n-1) d)
here a=first term and d=difference
Putting the values
1/5(60+(n-1)5)=52
By solving this we will get a quadratic equation-
n2+11n-104
By quadratic formula we get n=7
So time taken will be=12*7
72 minutes.
1/5(30+35....N)=52
This has become an A.P with a d=5
sn=n/2(2a+(n-1) d)
here a=first term and d=difference
Putting the values
1/5(60+(n-1)5)=52
By solving this we will get a quadratic equation-
n2+11n-104
By quadratic formula we get n=7
So time taken will be=12*7
72 minutes.