31.  An aeroplane covers a certain distance at a speed of 240 km/ph in5 hrs.To cover the same distance in1 2/3 hours it must travel at a speed of:


300 km/ph
720 km/hr
600 km/ph
360 km/hr


Answer

 Option

Distance = (240*5) km = 1200 km Required speed = (1200*3/5) km/hr = 720 km/hr

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32.  Anna left for city A from city B at 5.20 a.m. she traveled at the speed of 80 km/hr for 2 hours 15 minutes.After that speed was reduced to 60 km/hr.If the distance between two cities is 350 kms,at what time did Anna reach city A?


9.20.a.m
9.25 a.m
9.35 a.m
10.25 a.m


Answer

 Option

Distance covered in 2 hours 15 minutes i.e.2 1/4 hrs = (80*9/4) hrs = 180 hrs Time taken to cover remaining distance = (350-180/60) hrs = 17/6 hrs = 2 5/6 hrs = 2hrs 50 minutes Total time taken = 2 hrs 15 minutes + 2 hrs 50 minutes) = 5hrs 5 minutes So Anna reached city A at 10.25 a.m

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33.  A train covers a distance of 10 km in 12 minutes. If its speed is decreased by 5 km/hr the time taken by it to cover the same distance will be:


10 minutes
11 minutes 20 sec
13 minutes
13 minutes 20 sec


Answer

 Option

Speed = (10*60/12) km/hr = 50 km/hr New speed= (50-5) km/hr = 45 km/hr Time taken = (10/45) hr = (2/9*60) min = 13 1/3 min = 13 min 20 sec

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34.  The speed of a car increases by 2 km after everyone hour. If the distance traveled in the first one hour was 35 km, what was the total distance traveled in the first one hour was 35 km, what was the total distance traveled in 12 hours?


456 km
482 km
552 km
None of these


Answer

 Option

Total distance traveled in 12 hours = (35+37+39+..... up to 12 terms). This is an A.P. with first term, a = 35, number of terms, n=12, common difference, d=2. Therefore required distance = 12/2 (2*35+(12-1)*2) = 6(70+22) =552 km.

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35.  A motor car starts with the speed of 70 km/hr with its speed increasing every two hours by 10 kilo meter per hour. In many hours will it cover 345 kilometers?


2 1/4 hrs
4 hrs 5 min
4 1/2 hrs
None of these


Answer

 Option

Distance covered in first 2 hours = (70*2) km = 140 km. Distance covered in next 2 hours = (80*2) km = 160 km. Remaining distance = 345 - (140+160) = 45 km. Speed in the fifth hour = 90 km/hr. Time taken to cover 45 km = (45/90) hr = 1/2hr. Therefore total time taken = (2+2+1/2) = 4 1/2 hrs.

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