Aptitude contest - 68 with answers

[HELP]

1. A, Band C are on a trip by a car. A drives during the first hour at
an average speed of 50 km / hr. B drives during the next 2 hours at an
average speed of 48 km / hr. C drives for the next 3 hours at an
average speed of 52 km / hr. They reached their destination after
exactly 6 hours. Their mean speed was:



(a) 50 km /hr



(b) 50 1/3 km/hr



(c) 51 1/3m/hr



(d) 52 km/hr



2.A man on tour travels first 160 km at 64 km/ph next 160 km at 80
km/hr. The average speed for the first 320 km of the tour is :



(a) 35.55 km/hr



(b) 36 km/hr



(c) 71.11 km/hr



(d) 71 km/hr



3. A boy rides his bicycle 10 km at an average speed of 12 km/hr' and
again travels 12 km at an average speed of 10 km/ hr. His average speed
for the entire trip is approximately;



(a) 10.4 km/hr



(b) 10.8 km/hr



(c) 11 km/hr



(d) 12.2 km/hr



4. A man travels 600 km by train at 80 km/hr, 800 km by ship at 40
km/hr, 500 km by aeroplane at 400 km / hr and '100 km by car at 50 km /
hr. What is the average speed for the entire distance?



(a) 60 km /hr



(b) 60 5/123 km/hr



(c) 62 km/hr



(d) 65 5/123 km/hr



5. A car travels the first one-third of a certain distance with a speed
of 10 km / hr, the next one-third distance with a speed of 20 km / hr,
and the last one-third distance with a speed of 60 km / hr. The average
speed of the car for the whole journey is :



(a) 18 km/hr



(b) 24 km/hr .



(c) 30 km/hr



(d) 36 km/hr









Answers

1. b
2. c
3. b
4. d
5. a

Edited by: HELP

[anj_gtvr]

1)


total distance is 50*1+48*2+52*3=302


speed=302/6=50 1/3


2)total time 160/64+160/80=9/2

640/9=71.1

3)total time 10/12+12/10=244/60=61/30

speed=22/61/30=10.8

4)total time (600/80)+(800/40)+(500/400)+(100/50)

5)if total distance is 'x'

total time is=(x/3)/10+(x/3)/20+(x/3)/60=x/18

speed =x/x/18=18