Mathmetics
ISBT Mathmetics for all banking PO,Clerk,IBPS PO,Railway,SSC,IAS,OAS Exams
Q551. 

1)  285.71%  2)  283.71% 
3)  289.91%  4)  285.71% 
5)  None of these 
Answer : 285.71%
Explanation : Let ‘x’ be the number
Explanation : Let ‘x’ be the number
(35/100)x = 175
or x= (175 x 100)/35
So,required percentage = (500/75)/100 = 285.71%
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Q552. 

1)  200  2)  240 
3)  240  4)  500 
5)  None of these 
Answer : 200
Explanation :
Explanation :
Let, the full mark be x.
The first candidate's pass mark = (25/100)x +30
The second candidate's pass mark = ( 50/100 )x20
So, (25/100)x +30 = ( 50/100 )x20
Or x= 200
Shortcut Method :
FullMark = (Diff. in marks / diff.in %) x 100
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Q553.  In an election between two candidates, one got 55% of the total valid votes, 20% of the votes were invalid. If the total number of votes was 7500, the number of valid votes that the other candidate got, was: 
1)  2500  2)  2600 
3)  2700  4)  3000 
5)  None of these 
Answer : 2700
Explanation :
Explanation :
Number of valid votes = 80% of 7500 =
6000.
So, Valid votes polled by other candidate
= 45% of 6000
= (45/100 x 6000 = 2700.
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Q554.  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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Q555.  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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Q556.  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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Q557. 

1)  4  2)  5 
3)  6  4)  10 
5)  None of these 
Answer : 5
Explanation :
Explanation :
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Q558.  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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Q559. 

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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Q560. 

1)  8.5 km/hr  2)  9 km/hr 
3)  10 km/hr  4)  12.5 km/hr 
5)  None of these 
Answer : 10 km/hr
Explanation :
Explanation :
Man's rate in still water = (15  2.5) km/hr = 12.5 km/hr.
Man's rate against the current = (12.5  2.5) km/hr = 10 km/hr.
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