Mathmetics

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

Q531.
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.
View Answer

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) 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.
View Answer

Q533.
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.
View Answer

Q534.
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
View Answer

Q535.
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.
View Answer

Q536.
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.
View Answer

Q537.
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.
View Answer

Q538.
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.

View Answer

Q539.
The average weight of 8 person's increases by 2.5 kg when a new person comes in place of one of them weighing 65 kg. What might be the weight of the new person ?
1) 76 kg 2) 76.5 kg
3) 85 kg 4) Data Inadequate
5)None of these
Answer : 85 kg
Explanation :
Total weight increased = (8 x 2.5) kg = 20 kg.
So,weight of new person = (65 + 20) kg = 85 kg.
View Answer

Q540.
The average age of husband, wife and their child 3 years ago was 27 years and that of wife and the child 5 years ago was 20 years. The present age of the husband is:
1) 35 years 2) 40 years
3) 50 years 4) Data Inadequate
5)None of these
Answer : 40 years
Explanation :
Sum of the present ages of husband, wife and child = (27 x 3 + 3 x 3) years = 90 years.
Sum of the present ages of wife and child = (20 x 2 + 5 x 2) years = 50 years.
Husband's present age = (90 - 50) years = 40 years.
View Answer