Mathmetics
ISBT Mathmetics for all banking PO,Clerk,IBPS PO,Railway,SSC,IAS,OAS Exams
Q81.  There are 5 men and 3 women to form a committee of 5members where at least 3 men are there. How many way they can be selected ? 
1)  42  2)  45 
3)  46  4)  54 
5)  None of these 
Answer : 46
Explanation : Total ,5 men and 3 women i.e. 8 persons.
Explanation : Total ,5 men and 3 women i.e. 8 persons.
So, 3 men can selected from 5 men.
They can selected in (^{5}C_{3}_{ }x ^{3} C_{2} ) or (^{5}C_{4}_{ }x^{ 3} C_{1} ) or (^{5}C_{5}_{ }x ^{3 }C_{0} )
Total numbers of way to select = [(5 x 4 )/2 x 3 ] +[(5 ) x 3 ] + [(1x 1) ] = 46
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Q82.  The sum of two numbers is 27 and their H.C.F is 3. If one of the number is lies between 13 to 16, the find the value of the other number ? 
1)  12  2)  15 
3)  18  4)  24 
5)  None of these 
Answer : 12
Explanation : Let, two numbers are 3x and 3y respectively.
Explanation : Let, two numbers are 3x and 3y respectively.
Then, 3x + 3y = 27
or 3 (x + y) = 27
or (x + y) = 27/3 = 9
So, pairs of numbers are 9 = (1,8) , (2,7) , ( 3,6) and (4,5) .
Thus the numbers are 3 x 4 = 12 and 3 x 5 =15
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Q83. 

1)  Rs.820  2)  Rs.890 
3)  Rs.1020  4)  Rs.1250 
5)  None of these 
Answer : Rs.890
Explanation :
Explanation :
A : B : C = (8,000 x 6) : (4,000 x 8) : (8,000 x 8) = 48 : 32 : 64 = 3 : 2 : 4.
B's share = ( Rs. 4005/9) x 2 = Rs. 890.
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Q84. 

1)  Rs.1200  2)  Rs.1250 
3)  Rs.1450  4)  Rs.1500 
5)  None of these 
Answer : Rs.1500
Explanation :
Explanation :
Let, the total profit be Rs. 100.
After paying to charity, A's share = (Rs. 95 /5)x 3 = Rs. 57.
If A's share is Rs. 57, total profit = Rs. 100.
If A's share Rs. 855, total profit = ( 855/57) x100 = 1500
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Q85. 

1)  4 : 5  2)  5 : 4 
3)  3 : 2  4)  Data Inadequate 
5)  None of these 
Answer : 5 : 4
Explanation :
Explanation :
C.P. = S.P.  Profit
or C.P. = 5 1 = 4
or S.P. : C.P. = 5 : 4
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Q86. 

1)  Rs. 4,250  2)  Rs. 4,500 
3)  Rs. 6,400  4)  Rs. 7200 
5)  None of these 
Answer : Rs. 7200
Explanation :
Explanation :
We know that Sum = (S.I X 100 )/ R X T
= (Diff. in S.I X 100 ) / Diff. in rate X Time
= (72 X100)/ 2 X 5 = Rs. 7200.
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Q87. 

1)  5: 17  2)  1:11 
3)  11:1  4)  2:3 
5)  None of these 
Answer : 11:1
Explanation :
Explanation :
By alligation method :
2.40 3.60
2.50
3.60  2.50 2.50  2.40
= 1.10 10
So, Ratio will be 11 : 1.
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Q88. 

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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Q89. 

1)  456 km  2)  482 km 
3)  548 km  4)  552 km 
5)  None of these 
Answer : 552 km
Explanation :
Explanation :
Given, the first term, a = 35, common difference, d = 2 and total number of terms, (n) = 12.
The sum of this series will be the total distance travelled.
Sum, S_{n}= n/2[2a + (n  1) d] = 6 [70 + 11 x 2] = 552 km.
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Q90. 

1)  3  2)  5 
3)  9  4)  11 
5)  None of these 
Answer : 11
Explanation :
Explanation :
Let, the ten's digit be x and unit's digit be y.
Then, number = 10x + y.
Number obtained by interchanging the digits = 10y + x.
(10x + y) + (10y + x) = 11(x + y), which is divisible by 11.
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