Mathmetics
ISBT Mathmetics for all banking PO,Clerk,IBPS PO,Railway,SSC,IAS,OAS Exams
Q1.  The LCM and HCF of two numbers are 660 and 10 respectively. If the sum of the numbers is 170, the what should be difference of the numbers ? 
1)  30  2)  40 
3)  48  4)  50 
5)  None of these 
Answer : 50
Explanation : Let , two numbers are 10a and 10b ,where a and b are relatively prime numbers.
Explanation : Let , two numbers are 10a and 10b ,where a and b are relatively prime numbers.
According to the question,10a X b = 660
or ab = 66  (i)
Also given, 10a + 10b = 170
or a + b = 17  (ii)
Solving Eqs. (i) and (ii) we get a = 11 and b = 6
So, numbers are 110 and 60.
Thus, the difference is 110  60 = 50
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Q2. 

1)  288  2)  360 
3)  365  4)  435 
5)  None of these 
Answer : 365
Explanation : LCM of 6,8,9 and 10 is 360.
Explanation : LCM of 6,8,9 and 10 is 360.
So, total numbers of dozens of oranges are 360 +5 = 365
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Q3. 

1)  30  2)  31 
3)  32  4)  35 
5)  None of these 
Answer : 30
Explanation : HCF of 408 and 312 is 24.
Explanation : HCF of 408 and 312 is 24.
So, total numbers of sections = (408+312) /24 = 30
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Q4. 

1)  90 and 24  2)  120 and 24 
3)  120 and 54  4)  180 and 114 
5)  None of these 
Answer : 90 and 24
Explanation : The factors of 360 = 2 X 2 X 2 X 3 X 3 X 5
Explanation : The factors of 360 = 2 X 2 X 2 X 3 X 3 X 5
So, two numbers are 2 X 2 X 2 X 3 =24 and 2 X 3 X 3 X 5 = 90
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Q5.  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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Q6.  What is fourdigit largest number which when divided by 4, 5 , 6, 8 and 12 leaves reminder is zero in each case ? 
1)  9936  2)  9950 
3)  9960  4)  9990 
5)  None of these 
Answer : 9960
Explanation : The L.C.M of 4, 5 , 6, 8 and 12 is 120.
Explanation : The L.C.M of 4, 5 , 6, 8 and 12 is 120.
The fourdigit largest number is 9999.
Then, if 9999 is divided by 120, reminder is 39.
So, the require number = 9999  39 = 9960.
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Q7.  A rectangular size floor has 240 feet length and 200 feet wide. How many largest square size marbels slabs are require to pave ,so that no waste of slabs in the paving ? 
1)  24  2)  25 
3)  30  4)  36 
5)  None of these 
Answer : 30
Explanation : The H.C.F of 240 and 200 is 40.
Explanation : The H.C.F of 240 and 200 is 40.
Area of the floor = (240 X 200) square feet and area of the slab is (40X40) square feet.
So, Numbers of slabs require = (240 X 200)/(40X40) = 30.
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Q8.  A worker has paid Rs.4320 if he works for all day but he has paid Rs.2520 due to some days of absent in a month.How many days he was absent ? 
1)  2 days  2)  3 days 
3)  4 days  4)  5 days 
5)  None of these 
Answer : 5 days
Explanation : The H.C.F of 4320 and 2520 is 360.
Explanation : The H.C.F of 4320 and 2520 is 360.
So, 4320/360 = 12 days and 2520/360 = 7 days
Thus, numbers of he absent =127=5 days.
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Q9. 

1)  78  2)  91 
3)  104  4)  117 
5)  None of these 
Answer : 91
Explanation : Let, two numbers are 13x and 13y respectively.
Explanation : Let, two numbers are 13x and 13y respectively.
So, 13x X 13y = 13 X 455
or xy = 35
Then, pairs of numbers are 35 = (1 X 35) , (5 x 7).
So, second pairs is considerable i.e. 13X5 = 65 and 13 X 7 = 91
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Q10. 

1)  10  2)  12 
3)  15  4)  20 
5)  None of these 
Answer : 10
Explanation : Let, two numbers are 5x and 5y respectively.
Explanation : Let, two numbers are 5x and 5y respectively.
So, 5x X 5y = 5 X 495
or 25xy = 5 X 495
or xy = 99
So, pairs of numbers are i.e. 99 = (1 X 99) and (9 x 11)
Therefore , the satisfy numbers are 9 x 5 = 45 and 11 x 5 = 55
So, the difference is 55  45 = 10.
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