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

1)  215  2)  220 
3)  225  4)  235 
5)  None of these 
Answer : 225
Explanation : Given that, 45 H.C.F = L.C.M and
Explanation : Given that, 45 H.C.F = L.C.M and
H.C.F + L.C.M = 1150
or H.C.F + 45 H.C.F = 1150
or 46 H.C.F = 1150
or H.C.F = 1150/46 =25
So, L.C.M = 25 X 45 = 1125
Now, we can get 125 X x = 25 X 1125
or x = (25 X 1125) /125 = 225
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Q12. 

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.
So, required number = (1260 ÷ 2) = 630.
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Q13. 

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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Q14. 

1)  55/601  2)  12/55 
3)  11/120  4)  11/112 
5)  None of these 
Answer : 11/120
Explanation :
Explanation :
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Q15. 

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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Q16. 

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.
View Answer
Q17. 

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.
View Answer
Q18. 

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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Q19. 

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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Q20. 

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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