Latest self Aptitude Question SOLUTION: How much time is required to cover the distance of 910 Km by a car driver, if he start with the initial speed of 40 Km/hr. and increases the speed by 5 Km/hr for every next hour ?

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How much time is required to cover the distance of 910 Km by a car driver, if he start with the initial speed of 40 Km/hr. and increases the speed by 5 Km/hr for every next hour ?

Devendra Marghade (11 years ago)

Solved Aman Read Solution (4)

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Aman  (11 years ago)

IT is AP series problem where
a= 40, d=5 , sum = 910
and n=?

910 = (n/2)*(2*40+(n-1)*5)
5n^2+75n-1820=0
n^2+15n-364=0
solving it, we get
n=13

so 13 hours

Is this solution Helpfull? Yes (5) | No (1)  

Vignesh  (11 years ago)

13hrs need to cover the distance of 910km.

1st hour he crosses = 40km
2nd hour he crosses = 85km (since 5km/hr increases every hour)
3rd hour he crosses = 135km (since 5km/hr increases every hour)
..
..
..
..
..
12th hour he crosses = 810km (since 5km/hr increases every hour)
13th hour he crosses = 910km (since 5km/hr increases every hour)

i.e, 40+45+50+55+60+65+70+75+80+85+90+95+100 = 910km

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Vignesh  (11 years ago)

13 hours required to cover the distance of 910km.

Is this solution Helpfull? Yes | No (2)  

Arun  (11 years ago)

It can be solved by Arithmetic Progression.
a= 40, d=5 , sum = 910.
using the formul
S=n/2*(2d+(n-1)*5);
910 = (n/2)*(2*40+(n-1)*5)
5n^2+75n-1820=0
n^2+15n-364=0
solving it, we get
n=13 hrs (Ans)

Is this solution Helpfull? Yes | No (3)  

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