A bus covers its journey at the speed of 80km/hr in 10hours. If the same distance is to be covered in 4 hours, by how much the speed of bus will have to increase ?

Correct Answer: 4 kmph

Explanation:

Speed of Man = 4.5 kmph
Speed of stream = 1.5 kmph
Speed in DownStream = 6 kmph
Speed in UpStream = 3 kmph
Average Speed = (2 x 6 x 3)/9 = 4 kmph.

Correct Answer: 1 hr 20 min

Explanation:

Let the distance and original speed be 'd' km and 'k' kmph respectively.

d/0.8k - d/k = 20/60 => 5d/4k - d/k = 1/3

=> (5d - 4d)/4k = 1/3 => d = 4/3 k

Time taken to cover the distance at original speed

= d/k = 4/3 hours = 1 hour 20 minutes.

Correct Answer: 6

Explanation:

For this we have to find the LCM of 24, 36 and 30

LCM of 24, 36 and 30 = 360 sec

360/60 min = 6 minutes.

Correct Answer: 480 kms

Explanation:

Now, the distance covered by Chennai express in 2 hrs = 60 x 2 = 120 kms

Let the Charminar Express takes 't' hrs to catch Chennai express

=> 80 x t = 60 x (2 + t)

=> 80 t = 120 + 60t

=> t = 6 hrs

 

Therefore, the distance away from Hyderabad the two trains meet = 80 x 6 = 480 kms.

Correct Answer: 35 days

Explanation:

Distance d = 1200km
let S be the speed

he walks 15 hours a day(i.e 24 - 9)
so totally he walks for 70 x 15 = 1050hrs.

S = 1200/1050 => 120/105 = 24/21 => 8/7kmph

given 1 1/2 of previous speed
so 3/2 * 8/7= 24/14 = 12/7

New speed = 12/7kmph

Now he rests 10 hrs a day that means he walks 14 hrs a day.

time = 840 x 7 /12 => 490 hrs
=> 490/14 = 35 days

So he will take 35 days to cover 840 km.

Correct Answer: 41 sec

Explanation:

Speed = 44 kmph x 5/18 = 110/9 m/s

We know that, Time = distance/speed

Time = (360 + 140) / (110/9)

= 500 x 9/110 = 41 sec.

Correct Answer: 6:30 pm

Explanation:

Suppose they meet after 'h' hours

Then

3h + 4h = 17.5

7h = 17.5

h = 2.5 hours

So they meet at => 4 + 2.5 = 6:30 pm

Correct Answer: 80 km

Explanation:

Let the total distance be 'x' km.

Time taken to cover remaining 40% of x distance is    t 1 = 40 × x 100 × 48

But given time taken to cover first 60% of x distance is    t 2 = t 1 + 20 60 h r s

  $$\begin{gathered} t 2 = 60 × x 100 × 48 \\ \end{gathered}$$

? 60 × x 100 × 48 = 40 × x 100 × 48 + 20 60

 x=80 km.

Correct Answer: 40

Explanation:

Let distance = x km and usual rate = y kmph.
Then, x/y - x/(y+3) = 40/60 --> 2y (y+3) = 9x ----- (i)
Also, x/(y-2) - x/y = 40/60 --> y(y-2) = 3x -------- (ii)
On dividing (i) by (ii), we get:

x = 40 km.

Correct Answer: 5 kmph

Explanation:

Let p be the speed of man in kmph

According to the given data in the question,

Distance travelled by bus in 10 min with 20 kmph == Distance travelled by man in 8 min with (20 + p) kmph in opposite direction

=> 20 x 10/60 = 8/60 (20 + p)

=> 200 = 160 + 8p

=> p = 40/8 = 5 kmph.