Sample Questions For IAS - MENTAL ABILITY

STREAMS AND BOATS

• Assume speed of a boat is kmph and speed of a stream is kmph
• Then speed of the boat downsteam . Speed of the boat upstream

PIPES AND CISTERNS

• If one pipe can fill a tank in minutes and another can fill it in minutes, then amount of water in one minute when both pipes are opened
  

• Time taken by both pipes to fill the tank

• One pipe fills a cistern in minutes and another empties it in minutes. When both pipes are opened, amount of water in the cistern in one minute

• Time taken to fill the cistern

PROFIT AND LOSS

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• If a person sells part of his goods at profit % and part of his goods at profit % and the rest at a loss of %, the net profit or loss is

REVIEW QUESTIONS

1. A boat travels downstream through a distance of 20 km in 1 hr, but takes 2 hrs to travel the same distance upstream. What is the ratio of the speed of the boat to the speed of the current?
   1. 3:1
   2. 1:3
   3. 2:3
   4. 3:2
2. A man can row 3 kmph in still water. If the river is running at 0.5 kmph, it takes him 1 hr to row to a place and back. How far is the place?
   1. 1.4 km
      
   2. 1.47 km
   3. 1.46 km
   4. 1.458 km
3. A man can row 15 kmph in still water. It takes him twice as long to row up the river as it takes him to row down the river. Find the speed of the stream.
   1. 15 kmph
   2. 10 kmph
   3. 8 kmph
   4. 5 kmph
4. A stream has a current 2 kmph. A boat goes 10 km upstream and back again to the starting point in 55 min. What is the speed of the boat in still water?
   1. 22
   2. 23
   3. 25
   4. 24
5. A boat takes 6 hrs to go upstream but return in just two hours. If the speed of the current is 2 kmph, what is the speed of the boat?
   1. 4 kmph
   2. 3 kmph
   3. 5 kmph
   4. 6 kmph
6. A pipe can fill a tank in 12 hrs. Due to a leak in the bottom it is filled in 15 hrs. If the tank is full, how much time will it take for the leak to empty it?
   1. 30 hrs
   2. 60 hrs
   3. 1/30 hrs
   4. 1/60 hrs
7. Two pipes can fill a cistern in 4 hrs and 6 hrs respectively. When the pipes are opened simulatenously it is found that due to leakage in the bottom, 36 extra min are taken for the cistern to be filled up. When the cistern is full, in how much time will the leak empty it?
   1. 10
   2. 1/10
   3. 1/12
   4. 12
8. Three pipes A, B, C can independently fill a tank in 12, 15 and 20 hrs respectively. They were operated simulateneously for 4 hrs and then pipe B is closed. In what extra time would the tank fill up now?
   1. 1.6 hrs
   2. 1.7 hrs
   3. 1.5 hrs
   4. 2 hrs
9. Two pipes A and B can fill a tank in 20 mins, 25 mins respectively. If both pipes are opened simultaneously, after how much time should B be closed so that the tank fills in 15 min?
   1. 1 1/4
   2. 3 1/4
   3. 5 1/4
   4. 6 1/4
10. If two pipes function simultaneously, a reservoir will be filled in 12 hrs. One pipe fills the reservoir 10 hrs faster than the other. How many hours does it take the second to fill the reservoir?
    1. 30 hrs
       
    2. 12
    3. 40
    4. 3
11. A man sold a table at a profit of 15%. Had he bought it at 10% less and sold for Rs 21 less, he would have gained 25%. What is the cost price of the table?
    1. Rs 800
    2. Rs 840
    3. Rs 420
    4. Rs 1000
12. A girl sold 4/5th of her articles at a gain of 50% and the rest at par. Find her net loss or gain percent.
    1. 10
    2. 15
    3. 17
    4. 24
13. A man buys 5kg of apples for Rs 30 and sells at 3 kg for Rs 45. To gain Rs 180, how many kg must he sell?
    1. 15 kg
       
    2. 20 kg
       
    3. 25 kg
       
    4. 18 kg
       
14. A man has a gain of 25% when he sells a table at a certain price. If he had sold it at double the price, what would the gain percent have been?
    1. 120
    2. 140
    3. 130
    4. 150
15. A merchant sells a cloth at a 10% loss. He uses a duplicate scale and gains 15%. Find the false length of the scale. (Assume original measure 100 cm)
    1. 78.25 cm
    2. 78 cm
    3. 77.5 cm
    4. 91.5 cm

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