Mathmetics

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

Q531.
A motorboat, whose speed in 15 km/hr in still water goes 30 km downstream and comes back in a total of 4 hours 30 minutes. The speed of the stream (in km/hr) is:

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



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Q532.
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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Q533.
n one hour, a boat goes 11 km/hr along the stream and 5 km/hr against the stream. The speed of the boat in still water (in km/hr) is:
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.
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Q534.
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) 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 :
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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Q535.
A boat can travel with a speed of 13 km/hr in still water. If the speed of the stream is 4 km/hr, find the time taken by the boat to go 68 km downstream.
1) 2 hours 2) 3 hours
3) 4 hours 4) 5 hours
5)None of these
Answer : 4 hours
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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Q536.
In a stream that is running at 2 km/hr , a man goes 10 km upstream and comes back to the starting point in 55 min. Find the speed of the man in still water  ?
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 :
Let the speed of the man in still water be x km/hr. then,
 km/hr.
        10/(x-2) + 10/(x+2) = 55/60
        or  x = 22 km/hr
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Q537.
The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, then the weight of B is:
1) 17 kg 2) 20 kg
3) 26 kg 4) 31 kg
5)None of these
Answer : 31 kg
Explanation :
Let A, B, C represent their respective weights. Then, we have:
A + B + C = (45 x 3) = 135 .... (i)
A + B = (40 x 2) = 80 .... (ii)
B + C = (43 x 2) = 86 ....(iii)
Adding (ii) and (iii), we get: A + 2B + C = 166 .... (iv)
Subtracting (i) from (iv), we get : B = 31.
B's weight = 31 kg.
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Q538.
The average monthly income of P and Q is Rs. 5050. The average monthly income of Q and R is Rs. 6250 and the average monthly income of P and R is Rs. 5200. The monthly income of P is:
1) 3500 2) 4000
3) 4050 4) 5000
5)None of these
Answer : 4000
Explanation :
Let P, Q and R represent their respective monthly incomes. Then, we have:
P + Q = (5050 x 2) = 10100 .... (i)
Q + R = (6250 x 2) = 12500 .... (ii)
P + R = (5200 x 2) = 10400 .... (iii)
Adding (i), (ii) and (iii), we get:  2(P + Q + R) = 33000  or   P + Q + R = 16500 .... (iv)
Subtracting (ii) from (iv), we get P = 4000.
P's monthly income = Rs. 4000.
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Q539.
The average monthly income of P and Q is Rs. 5050. The average monthly income of Q and R is Rs. 6250 and the average monthly income of P and R is Rs. 5200. The monthly income of P is:
1) 3500 2) 4000
3) 4050 4) 5000
5)None of these
Answer : 4000
Explanation :
Let P, Q and R represent their respective monthly incomes. Then, we have:
P + Q = (5050 x 2) = 10100 .... (i)
Q + R = (6250 x 2) = 12500 .... (ii)
P + R = (5200 x 2) = 10400 .... (iii)
Adding (i), (ii) and (iii), we get:  2(P + Q + R) = 33000  or   P + Q + R = 16500 .... (iv)
Subtracting (ii) from (iv), we get P = 4000.
P's monthly income = Rs. 4000.
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Q540.
The captain of a cricket team of 11 members is 26 years old and the wicket keeper is 3 years older. If the ages of these two are excluded, the average age of the remaining players is one year less than the average age of the whole team. What is the average age of the team ?

1) 23 years 2) 24 years
3) 25 years 4) 30 years
5)None of these
Answer : 23 years
Explanation :
        Let the average age of the whole team by x years.
Then,11x - (26 + 29) = 9(x -1)
or 11x - 9x = 46
or 2x = 46
or x = 23.
So, average age of the team is 23 years.

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