Mathmetics
ISBT Mathmetics for all banking PO,Clerk,IBPS PO,Railway,SSC,IAS,OAS Exams
Q1. 

1)  2  2)  4 
3)  6  4)  8 
5)  None of these 
Answer : 6
Explanation :
Explanation :
Let,speed of boat man be x kmph.
So, speed in down stream =(x+2) kmph. and speed in upstream = (x2) kmph.
Since, distance is constant for both case ,
the equation = 2(x2) = (x+2)
or 2x4 = x+2
or x= 6 kmph
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Q2. 

1)  1 km/hr.  2)  1.5 km/hr. 
3)  2 km/hr.  4)  3 km/hr. 
5)  None of these 
Answer : 1.5 km/hr.
Explanation :
Explanation :
Let, the speed of the stream be x km/hr.
Then, upward speed =(5 x)km/hr.
downward speed = (5 + x) km/hr.
So, (15/5+x) + (9/5x) = 5
or x = 2 km/hr
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Q3. 

1)  3 km/hr.  2)  4 km/hr. 
3)  6 km/hr.  4)  8 km/hr 
5)  None of these 
Answer : 3 km/hr.
Explanation :
Explanation :
Let, the speed of the stream be x km/hr.
Then, (91/10x) + (91/10+x) = 20
or x = 3 km./hr
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Q4. 

1)  4 km/hr  2)  6 km/hr 
3)  8 km/hr  4)  12 km/hr. 
5)  None of these 
Answer : 8 km/hr
Explanation :
Explanation :
Let, the speed of the man in still water be x km/hr and speed of the stream be y km/hr, then
(30/xy) + (44/x+y) = 10 ......... (i)
(40/xy) + (55/x+y) = 13 ........ (ii)
Solving equation. (I) and (II), we get x = 8 km/hr y = 3 km/hr
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Q5.  A man takes twice as long to row a distance against the stream as to row the same distance in favour of the stream. The ratio of the speed of the boat (in still water) and the stream is: 
1)  2:1  2)  3:2 
3)  2:3  4)  3:1 
5)  None of these 
Answer : 3:1
Explanation :
Explanation :
Let man's rate upstream be x kmph.
Then, his rate downstream = 2x kmph.
(Speed in still water) : (Speed of stream) = (2x+2) /2 : (2xx)/2
=3x/2: x/2 = 3 : 1.
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Q6.  A boat covers a certain distance downstream in 1 hour, while it comes back in 1 hours. If the speed of the stream be 3 kmph, what is the speed of the boat in still water ? 
1)  10kmph  2)  12kmph 
3)  15kmph  4)  18kmph 
5)  None of these 
Answer : 15kmph
Explanation :
Explanation :
Let the speed of the boat in still water
be x kmph. Then,
Speed downstream = (x + 3) kmph,
Speed upstream = (x  3) kmph.
(x
+ 3) x 1 = (x  3)/2 x3
Or 2x + 6 = 3x  9
Or x = 15 kmph.
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Q7.  A man can row at 5 kmph in still water. If the velocity of current is 1 kmph and it takes him 1 hour to row to a place and come back, how far is the place ? 
1)  2.4 km  2)  2.5km 
3)  3km  4)  3.6km 
Answer : 2.4 km
Explanation :
Explanation :
Speed downstream = (5 + 1) kmph = 6 kmph.
Speed upstream = (5  1) kmph = 4 kmph.
Let the required distance be x km.
Then,x/6 +x/4 = 1
Or
2x + 3x = 12
Or 5x = 12
Or x = 2.4 km.
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Q8. 

1)  4  2)  5 
3)  6  4)  10 
5)  None of these 
Answer : 5
Explanation :
Explanation :
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Q9.  A man's speed with the current is 15 km/hr and the speed of the current is 2.5 km/hr. The man's speed against the current is: 
1)  7.5 km/hr  2)  8.5 km/hr 
3)  10 km/hr  4)  12.5 km/hr 
5)  None of these 
Answer : 10 km/hr
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Q10. 

1)  3 km/hr  2)  5 km/hr 
3)  8 km/hr  4)  9 km/hr 
5)  None of these 
Answer : 8 km/hr
Explanation : Speed in still water = ½(11 + 5) kmph = 8 kmph.
Explanation : Speed in still water = ½(11 + 5) kmph = 8 kmph.
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