Mathmetics
ISBT Mathmetics for all banking PO,Clerk,IBPS PO,Railway,SSC,IAS,OAS Exams
Q11. 

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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Q12. 

1)  2 hours  2)  3 hours 
3)  4 hours  4)  5 hours 
5)  None of these 
Answer : 4 hours
Explanation :
Explanation :
Speed downstream = (13 + 4) km/hr = 17 km/hr.
Time taken to travel 68 km downstream = ( 68/17) hrs = 4 hrs.
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Q13. 

1)  20 km/hr  2)  22 km/hr 
3)  24 km/hr  4)  28 km/hr 
5)  None of these 
Answer : 22 km/hr
Explanation :
Explanation :
Let the speed of the man in still water be x km/hr. then,
km/hr.
10/(x2) + 10/(x+2) = 55/60
or x = 22 km/hr
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Q14.  A boat running downstream covers a distance of 24 kms in 4hrs while for covering the distance upstream it takes 6 hrs. What is the speed of the boat in still water ? 
1)  5.5 km/hr  2)  6 km/hr 
3)  3.5 km/hr  4)  4.5 km/hr 
5)  None of these 
Answer : None of these
Explanation : Ans. 5 km/hr
Explanation : Ans. 5 km/hr
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