Quiz-1

Let's assume the two trains be A and B.

For train A:

Speed = 60km/hr i.e. In 60km in 1 hr and 30km in 30 mins.
At 10:00 am = Distance covered is 0km.
At 10:30 am = Distance covered is 30km.
At 11:00 am = Distance covered is 60km.
At 11:30 am = Distance covered is 90km.
At 12:00 pm = Distance covered is 120km.
At 12:30 pm = Distance covered is 150km.

Similarly For train B:

Speed = 75km/hr i.e. In 75km in 1 hr and 37.5km in 30 mins.
At 10:30 am = Distance covered is 0km.
At 11:00 am = Distance covered is 37.5km.
At 11:30 am = Distance covered is 75km.
At 12:00 pm = Distance covered is 112.5km.
At 12:30 pm = Distance covered is 150km.

Therefore, both the trains meet at 12:30 pm and after traveling 150km.

 

28 children can do a piece of work in 50 days

⇒ 50 days = 28 children

The number of days is inversely proportional to the number of children.

⇒ The more days we have, the fewer children we need

Find number of children needed to complete the work in 1 day:

50 days = 28 children

1 day = 28 x 50 = 1400 children

Find number of children needed to complete the work in 30 day:

1 day = 1400 children

30 days = 1400 ÷ 30 = 46.67 ≈ 47 complete days

Answer: 30 children will need 47 days to complete the work.

 

A's Speed:B's Speed=rootof(b):rootof(a)
=>8:x=rootof(10/3):rootof(16/3)
On solving we get,
=> x=2*rootof(10)
=> x=2*3.16
=> x=6.32 kmph.

15 days
Work = 28 * 6 * 15 --- (1)
Work = 21 * 8 * x -- - (2)
Equating (1) and (2)
28 * 6 * 15 = 21 * 8 * x
X= 15

200 m
Speed = distance/time;
Distance= speed * time
= (60-45) * 48 * ( 5/18)
( relative speed in same direction is s1-s2 and kmph to m/sec 5/18)
= 200m

Length of the Train = 240 m.

Time taken by it to cross the Pole = 15 seconds.

∵ Speed = Distance or length of the train/Time

∴ Speed = 240/15

⇒ Speed of the train = 16 m/s

= 16×3.6 km/h

= 57.6 km/h

The speed of the train is 57.6 km/h.

 

Let length of platform = P m
we know,
distance = speed × time
here,
time = 1.5 × 60 sec = 90 sec
speed = 54 × 5/18 = 15 m/s
distance = (1200 + P) m

1200 + P = 15 × 90
1200 + P = 1350
P = 150 m

hence, Length of platform = 150 m

Let the speeds of the trains be A and B and
their length be L
A = L/4
B = L/5
now when they move in same direction
to cross one train, the other train has to cover 2L distance
now
relative velocity = L/4 - L/5 = L/20
therefore time taken = 2L/L/20 = 40 sec

Between 100 and 700

With 60 kmph in 3 hours train ‘A’ covers 180 kms.

Train B speed is 12kmph more than train ‘A’.
Because train B started 3 hours later so it has to cover 180
extra with extra 12kmph speed.
Time taken is = 180/12 = 15 hours
So 15 hours from 2p.m is 5a.m on the next day