Mathmetics
ISBT Mathmetics for all banking PO,Clerk,IBPS PO,Railway,SSC,IAS,OAS Exams
Q21.  The simple interest per annum on an amount of Rs.17,000 at the end of four years is Rs.6800. What would be the compound interest on the same amount at the same rate after 2 years ? 
1)  Rs.3240  2)  Rs.3470 
3)  Rs.3570  4)  Can'not be determined 
5)  None of these 
Answer : Rs.3570
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Q22.  The ratio between A's and Bs salary was 3:4,two year ago . The ratio's of individual salaries of A and B two year's ago and this year's salaries are 4:5 and 2:3 respectively. At present the total of their salary is Rs.4290. What is present salary of A ? 
1)  Rs.1560  2)  Rs.1600 
3)  Rs.1650  4)  Rs.1840 
5)  None of these 
Answer : Rs.1650
Explanation :
Explanation :
Let, two year ago ,the ratio of between A'and B's salary was 3x: 4x respectively.
The ratio of their individual salary between two years ago and this year is 4y:5y and 2z:3z respectively.
So, 4y = 3x (A's last year salary)
or y = .75x and 2z = 4x (B's last year salary)
or z = 2x
Now, the total of their salary is Rs.4290 .
So, 5y + 3z = Rs.4290
Replace y with .75x; replace z with 2x
So, 5(.75x) + 3(2x) = 4290
or 3.75x + 6x = Rs.4290 or 9.75x = 4290
or x = 4290/9.75 = 440
Then, A's present salary 3.75 (440) = Rs.1650
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Q23. 

1)  8 days  2)  10 days 
3)  12 days  4)  14 days 
5)  None of these 
Answer : 14 days
Explanation : Let, Bikas takes x days to finish the work . So, Alok would take (x +8) days to finish the same work.
Explanation : Let, Bikas takes x days to finish the work . So, Alok would take (x +8) days to finish the same work.
Given, Alok finishes 75% and Bikas finishes 25% work respectively.
So, (x+8)3/4 = (x/4)+9
or (3x+24)/4 = (x+36)/4
or 2x = 12
or x = 6
Therefore, Alok would finishes the work (6+8) = 14 days alone.
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Q24.  A person sold two hens for Rs. 105 each . On one he lost 25% . On the other he gained 50% . What is the gain or loss on his total outlay ? 
1)  12.5%  2)  20% 
3)  28.3%  4)  Neither gain Nor loss 
5)  None of these 
Answer : Neither gain Nor loss
Explanation : ShortCut Method:
Explanation : ShortCut Method:
[100 x (Profit  Loss ) x 2 x Profit x Loss] / (100 + Profit ) + (100  Loss) = 0%
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Q25. 
A sells his books cost Rs.500 to B at a profit of 30%. After some period of time, B sells the same book to A at a loss of 20%. What is the total % of profit or loss in the whole trading ? 
1)  4% profit  2)  4% loss 
3)  26% profit  4)  26% loss 
5)  None of these 
Answer : 26% profit
Explanation : Let, CP of A = 100 , SP of B from A = 130 i.e. profit = 30/
Explanation : Let, CP of A = 100 , SP of B from A = 130 i.e. profit = 30/
Again , some days B sells in return to A at loss of 20% i.e. the CP of A again = 130 x (80/100) = 104
So ,in the whole trade , he gets actual profit = (304) = 26 i.e. 26%
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Q26.  Two partners invested Rs.20,000 and Rs.12,000 respectively in a business.They distribute 75% of the profit equally and distribute the rest 25% according to the ratio of their investment of capitals. If the bigger partner received Rs.400 more than the other, then what is the total profit ? 
1)  Rs.5280  2)  Rs.5600 
3)  Rs.6240  4)  Rs.6400 
5)  None of these 
Answer : Rs.6400
Explanation : Since, 75% of the profit is distributed equally ,rest 25% should be distributed according to their ratio of investment.
Explanation : Since, 75% of the profit is distributed equally ,rest 25% should be distributed according to their ratio of investment.
Actual, ratio of capital = 20000:12000 = 5:3
5/8  3/8 = 400
or 2/8 = 1/4 = 400
or 1 = 4 x 400 = 1600 i.e. 25%
So, total profit = 400 x 4 x (1/25) x 100 = 6400
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Q27.  The L.C.M and H.C.F of two numbers are 660 and 10 respectively. If the sum of the numbers is 170, what is the difference between the numbers ? 
1)  50  2)  56 
3)  60  4)  64 
5)  None of these 
Answer : 50
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Q28. 

1)  1 : 6  2)  1 : 5 
3)  1 : 25  4)  1 : 125 
5)  None of these 
Answer : 1 : 5
Explanation :
Explanation :
The volume of the larger cube = 53 = 125 cm^{3}.
The volume of each of the smaller cubes = 13 = 1 cm^{3}.
Therefore, one would get 125 smaller cubes.
The surface area of the larger cube = 6a^{2} = 6(52) = 6 25 = 150
The surface area of each of the smaller cubes = 6 (12) = 6.
Therefore, surface area of all of the 125, 1 cm^{3} cubes = 125 6 = 750.
Therefore, the required ratio = 150 : 750 = 1 : 5
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Q29. 
1)  8  2)  9 
3)  10  4)  12 
5)  None of these 
Answer : 10
Explanation :
Explanation :
Given, x^{2} + 9/x = 6x
Or x^{2}  6x = 9
Or (x3)^{2} = 0
Or x = 3
So, x^{2} + 9/x^{2 }= 10
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Q30. 

1)  221  2)  231 
3)  253  4)  0 
5)  None of these 
Answer : 253
Explanation :
Explanation :
Given, a = 4/3
Or 3a = 4
Or 3a  4 = 0
Or (3a4)^{3} = 27a^{3}  108a^{2} + 144a  64 = 0^{3}
Or 27a^{3}  108a^{2} + 144a  317 = (27a^{3}  108a^{2} + 144a 64)  153 = 0  253 =  253
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