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Q:

If 20 men can build a wall 56 meters long in 6 days , what length of  a similar wall can be  built by 35 men in 3 days?

A) 46 B) 47
C) 48 D) 49
 
Answer & Explanation Answer: D) 49

Explanation:

Let the required length be x meters

 More men, More length built     (Direct proportion) 

Less days, Less length built      (Direct Proportion)

Men20:35Days6 : 3 56 :x 

=> (20 x 6 x X)=(35 x 3 x 56) 

=> x = 49 

Hence, the required length is 49 m.

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Filed Under: Chain Rule

Q:

A contractor undertakes to do a piece of work in 40 days. He engages 100 men at the begining and 100 more  after 35 days and completes the work in stipulated time. If he had not  engaged  the additional men, how many days  behind schedule would it be finished?

A) 3 B) 5
C) 6 D) 9
 
Answer & Explanation Answer: B) 5

Explanation:

[(100 x 35) + (200 x 5)]men can finish the work in 1 day 

Therefore, 4500 men can finish the work in 1 day. 100 men can finish it in  4500/100= 45 days.

This is 5 days behind Schedule

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Filed Under: Chain Rule

Q:

If the Price of 6 toys is Rs. 264.37, What will be the approximate  price of 5 toys?

A) Rs.120 B) Rs.100
C) Rs.200 D) Rs.220
 
Answer & Explanation Answer: D) Rs.220

Explanation:

Let the required Price be Rs. X .Then, Lest toys , Less cost  (Direct Proportion) 

Therefore 6 : 5  :: 264.37 : x

=> 6 * x = 5 * 264.37

=> X= 220.308

Therefore,  Approximate price of 5 toys = Rs. 220

 

 

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Q:

Shahrukh starts from Barabanki to Fatehpur , 1 hour after Ajay starts. Shahrukh meets Kajol 1.5 hours after Shahrukh starts. If the speed of Shahrukh is at least 20km/h faster than the speed of Kajol.

What is the minimum speed of Shahrukh to overtake Ajay, before he meets Kajol?

A) 30 B) 40
C) 60 D) None of these
 
Answer & Explanation Answer: D) 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.

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Filed Under: Time and Distance

Q:

A boat sails 15 km of a river towards upstream in 5 hours. How long will it take to cover the same distance downstream, if the speed of current is one-fourth the speed of the boat in still water:

A) 1.8h B) 3h
C) 4h D) 5h
 
Answer & Explanation Answer: B) 3h

Explanation:

Upstream speed = B-S

Downstream speed = B+s

B-S = 15/5 = 3 km/h

Again          B= 4S

Therefore    B-S = 3= 3S

=>             S = 1 and B= 4 km/h

Therefore    B+S = 5km/h

Therefore, Time during downstream = 15/5 = 3h

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Filed Under: Boats and Streams

Q:

Two horses start trotting towards each other, one from A to B and another from B to A. They cross each other after one hour and the first horse reaches B, 5/6 hour before the second horse reaches A. If the distance between A and B is 50 km. what is the speed of the slower horse?

A) 30 km/h B) 15 km/h
C) 25 km/h D) 20 km/h
 
Answer & Explanation Answer: D) 20 km/h

Explanation:

If the speed of the faster horse be fs and that of slower horse be ss then

 fs+ss=501=50 

and       50ss-50fs=56

Now, you can go through options.

The speed of slower  horse is 20km/h

Since,   20+30=50

and  5020-5030=56    

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Filed Under: Time and Distance

Q:

A train of length 250 m crosses a bridge of length 150m in 20 seconds. What is the speed of train?

Answer

Sol : (length of train+ length of bridge) = speed of train x Time


        (250+150) = 20 x Speed


        Speed = 400/20= 20 m/s =72 km/h

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Q:

A contractor  undertook a project to complete it in 20 days which needed 5 workers to work continuously for all the days estimated. But before the start of the work the client wanted to complete it earlier than the scheduled time, so the contractor calculated that  he needed to increase 5 additional  men every 2 days to complete the work in the time the client wanted it:

If the work was further increased by 50% but the contractor continues to increase the 5 workers o every 2 days then how many more days are required over the initial time specified by the  client.

A) 1 day B) 2 days
C) 5 days D) None of these
 
Answer & Explanation Answer: B) 2 days

Explanation:

Total work = 100+50 = 150man-days

In 8 days 100 man-days work  has been completed. Now on 9th and 10th day there will be 25 workers. So in 2 days they wll complete additional 50 man- days work. Thus the work requires 2 more days.

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Filed Under: Time and Work