A machine puts c caps on bottles in m minutes. How many hours will it take to put caps on b bottles

Correct Answer: 17 hours

Explanation:

In this type of questions we need to get the relative speed between them,
The relative speed of the boys = 5.5kmph ? 5kmph
= 0.5 kmph

Distance between them is 8.5 km
Time = Distance/Speed
Time= 8.5km / 0.5 kmph = 17 hrs

Correct Answer: 99

Explanation:

Let, Distance between A and B = d

 

Distance travelled by P while it meets Q = d + 11

 

Distance travelled by Q while it meets P = d ? 11

 

Distance travelled by Q while it meets R = d + 9

 

Distance travelled by R while it meets Q = d ? 9

 

Here the ratio of speeds of P & Q => SP : SQ = d + 11 : d ? 11

 

The ratio of speeds of Q & R => SQ : SR = d + 9 : d ? 9

 

But given Ratio of speeds of P & R => P : R = 3 : 2

  S P S R = S P S Q x S Q S R = d + 11 d + 9 d - 11 d - 9

 

=>  d + 11 d + 9 d - 11 d - 9 = 3/2

 

=>  d = 1, 99

 

=> d = 99 satisfies.

 

Therefore, Distance between A and B = 99

Correct Answer: 27 sec

Explanation:

Time taken to meet for the first time anywhere on the track

= length of the track / relative speed

= 300 / (15 + 25)5/18 = 300x 18 / 40 x 5 = 27 seconds.

Correct Answer: None of these

Explanation:

Let t be the time after Kajol starts, when she meets Ajay, then 

               t = 300/(x+y) 

 This should be less than 2.5 or (x+y)>120 

Since       y= 3x/2  =>  y > 72

This (y>72) is greater than 67.5 km/h and hence Shahrukh will always overtake Ajay before he meets Kajol.

Correct Answer: 48 kmph

Explanation:

Let the initial speed of Akhil be '4p' kmph

Then speed after decrease in speed = '3p' kmph

We know that, 

Change in speed == Change in time

According to the given data,

$$\begin{gathered} 24 3 p - 24 4 p = 35 - 25 60 \\ = > p = 12 \end{gathered}$$

 

Hence, the initial speed of Akhil = 4p = 4 x 12 = 48 kmph.

Correct Answer: 6 mile/hr

Explanation:

Let the speed of river and boat be 'r' m/min and 'b' m/min.
so relative speed in upstream (b-r)m/min and in downstream (b+r)m/min.
Now in upstream distnce covered in 5 min is 5(b-r)miles
so total distnce covered => 1 + 5(b-r)miles in upstream
In downstream distance covered in 5min is 5(b+r)miles
Now 1 + 5(b-r) = 5(b+r)
1+5b-5r = 5b+5r
1 = 10r
r = 1/10 mile/min => 6 mile/hr.

Correct Answer: 330/29 m/s

Explanation:

Second gun shot take 30 sec to reach rahul imples distance between two.

given speed of sound = 330 m/s

Now, distance = 330 m/s x 30 sec 

 

Hence, speed of the bus = d/t = 330x30/(14x60 + 30) = 330/29 m/s.

Correct Answer: 12 kmph

Explanation:

The distance is constant in this case.

Let the time taken for travel with a speed of 10 kmph be 't'.

Now the speed of 15 kmph is 3/2 times the speed of 10 kmph.

Therefore, time taken with the speed of 15 kmph will be 2t/3 (speed is inversely proportional to time)

Extra time taken = t - 2t/3 = t/3

=> 1pm - 11am = 2hrs

=> t/3 = 2h

=> t = 6 hrs.

Now, Distance = speed x time = 10 x 6 = 60 kms

Time he takes to reach at noon = 6 - 1 = 5 hrs

Now, Speed = 60/5 = 12 kmph.

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: 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.