Mathmetics
ISBT Mathmetics for all banking PO,Clerk,IBPS PO,Railway,SSC,IAS,OAS Exams
Q571. 

1)  34  2)  31 
3)  36  4)  32 
5)  None of these 
Answer : 36
Explanation :
Explanation :
Let the batsman’s average runs up to 12th innings was x.
Total run = 12 x.
Now total run up to 13th innings = (12 x + 96)
According to equation = (12 x + 96)/13 = x + 5 or x = 31.
So, after 13th innings average will be 31 + 5 = 36.
Shortcut Method :
96  (135) + 5 = 36
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Q572. 

1)  500  2)  600 
3)  550  4)  480 
5)  None of these 
Answer : 550
Explanation :
Explanation :
By alligantion method :
12000 3750
6000
6000  3750 = 2250 12000  6000 = 6000
So, final ratio = 2250 : 6000 = 3 : 8
So,total number of employees = (150/3) x 11 = 550
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Q573. 

1)  3:5  2)  1:1 
3)  4:5  4)  D.I 
5)  None of these 
Answer : 1:1
Explanation :
Explanation :
With the help of alligation method :
50 40
45
45  40 = 5 50  45 = 5
So, final ratio = 5 : 5 = 1 : 1
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Q574. 

1)  279  2)  283 
3)  308  4)  318 
5)  None of these 
Answer : 308
Explanation : We know that H.C.F x L.C.M = Product of two numbers
Explanation : We know that H.C.F x L.C.M = Product of two numbers
So,other number = (11 x 7700)/275 = 308.
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Q575. 

1)  1677  2)  1683 
3)  2523  4)  3363 
5)  None of these 
Answer : 1683
Explanation :
Explanation :
L.C.M. of 5, 6, 7, 8 = 840.
Required number is of the form 840k + 3
Least value of k for which (840k + 3) is divisible by 9 is k = 2.
Required number = (840 x 2 + 3) = 1683.
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Q576. 

1)  196  2)  630 
3)  1260  4)  2520 
5)  None of these 
Answer : 630
Explanation :
Explanation :
L.C.M. of 12, 18, 21 30 = 1260.
Required number = (1260 ÷ 2) = 630.
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Q577. 

1)  1  2)  2 
3)  3  4)  4 
5)  None of these 
Answer : 2
Explanation :
Explanation :
Let the numbers 13a and 13b.
Then, 13a x 13b = 2028
ab = 12.
Now, the coprimes with product 12 are (1, 12) and (3, 4).
So, the required numbers are (13 x 1, 13 x 12) and
(13 x 3, 13 x 4).
Clearly, there are 2 such pairs.
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Q578. 

1)  20  2)  23 
3)  169  4)  400 
5)  None of these 
Answer : 23
Explanation :
Explanation :
Let the numbers be x and y.
Then, xy = 120 and x^{2} + y^{2 }= 289.
(x + y)^{2} = x^{2} + y^{2 }+ 2xy = 289 + (2 x 120) = 529
x + y = 23.
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Q579. 

1)  101  2)  107 
3)  111  4)  185 
5)  None of these 
Answer : 111
Explanation :
Explanation :
Let the numbers be 37a and 37b.
Then, 37a x 37b = 4107
ab = 3.
Now, coprimes with product 3 are (1, 3).
So, the required numbers are (37 x 1, 37 x 3) i.e., (37, 111).
Greater number = 111.
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Q580. 

1)  40  2)  80 
3)  120  4)  200 
5)  None of these 
Answer : 40
Explanation :
Explanation :
Let the numbers be 3x, 4x and 5x.
Then, their L.C.M. = 60x.
So, 60x = 2400 or x = 40.
The numbers are (3 x 40), (4 x 40) and (5 x 40).
Hence, required H.C.F. = 40.
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