Mathmetics
ISBT Mathmetics for all banking PO,Clerk,IBPS PO,Railway,SSC,IAS,OAS Exams
Q21. 

1)  10  2)  20 
3)  29  4)  30 
Answer : 30
Explanation :
Explanation :
Bag X:
Two balls taken from bag x, total probability,
According to the question,
40/87 = (Probability of getting 1st green and second blue * Probability of getting 1st blue and
second green)
Take green = 10 and blue = 20
According to the question,
40/87 = 10 * 20 * 2/(30 * 29)
40/87 = 40/87
This satisfies the given condition.
So, total number balls in box X should be 30.
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Q22. 

1)  2/29  2)  3/29 
3)  4/29  4)  5/29 
Answer : 3/29
Explanation :
Explanation :
Bag X:
Two balls taken from bag x, total probability,
According to the question,
40/87 = (Probability of getting 1st green and second blue * Probability of getting 1st blue and second green)
Take green = 10 and blue = 20
According to the question,
40/87 = 10 * 20 * 2/(30 * 29) or 40/87 = 40/87
This satisfies the given condition.
Probability of both green ball (A) = 10C2/30C2
= (10 * 9)/(29 * 30) = 3/29
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Q23. 

1)  60 days  2)  80 days 
3)  90 days  4)  120 days 
5)  None of these 
Answer : 90 days
Explanation : Total workers = 0.5Z * 2 M = 0.5 * (1.2 M) * 2 M = 1.2 M2 Total work = M2 * 108 = 1.2 M2 * No of days = > No of days = (M2 * 108) / (1.2 M2 ) = 90 days
Explanation : Total workers = 0.5Z * 2 M = 0.5 * (1.2 M) * 2 M = 1.2 M2 Total work = M2 * 108 = 1.2 M2 * No of days = > No of days = (M2 * 108) / (1.2 M2 ) = 90 days
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Q24. 

1)  33 days  2)  22 days 
3)  36 days  4)  44 days 
5)  None of the 
Answer : 33 days
Explanation :
M_{1} * D_{1} = M_{2} * D_{2}
Explanation :
Solutions:
Project A:
X * 88 = (X + 8) * 66
= > 88X = 66X + 8 * 66 = > 22X = 8 * 66 = > X = 24
Project B:
Y * (Y  1) = (Y + 6) * (Y  6)
Y^{2} – Y = Y^{2} – 6^{2}
= > Y = 36
Project C:
Z^{2} * 75 = M^{2} * 108
= > Z^{2} / M^{2} = 108/75
= > Z^{2} / M^{2} = 36/25
= > Z / M = 6/5
= > Z = 6/5 * M
= > Z = 1.2 M
24 * 88 = 64 * D2
= > D_{2} = (24 * 88)/64
= > D_{2} = 33 days
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Q25. 

1)  40  2)  42 
3)  45  4)  48 
Answer : 45
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Q26. 

1)  I and II together  2)  Only II 
3)  I and II together  4)  I and either II or III 
5)  Any two statements together. 
Answer : Any two statements together.
Explanation : Explanations : Let speed of boat in sill water be x kmph and velocity of stream be y kmph respectively.
Explanation : Explanations : Let speed of boat in sill water be x kmph and velocity of stream be y kmph respectively.
So, from I , we get x+y = 5kmph
From II, it given y = 2x/3 , we get x = 3kmph and y = 2kmph
From III, w get, x  y = 2.5 kmph
Therefore, to find out the speed of the boat any two statements together is sufficient.
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Q27.  A rectangular container, whose base is square of side 15cm,stands on a horizontal table and holds water up to 3cm from the top. When a cube is placed in the water and is completely submerged, the water rises to the top and 54cm^3 of water overflows. What is its surface area? 
1)  448cm2  2)  464cm2 
3)  486cm2  4)  524cm2 
5)  None of these 
Answer : 486cm2
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Q28.  The length of a rectangle increases by 20% and also its breadth increases by 15% . What should be the percentage change in its perimeter? 
1)  35%  2)  36% 
3)  38%  4)  Can't be determined 
5)  None of these 
Answer : Can't be determined
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Q29.  A is 25% more efficient than B and 50% more efficient than C. A and B together can complete a work in 20 days. How many days the same work can be completed by B and C if both work in alternate days and B starts the work first ? 
1)  48 days  2)  49 days 
3)  50 days  4)  51 days 
5)  None of these 
Answer : 49 days
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Q30. 

1)  Rs.6400  2)  Rs.6500 
3)  Rs.7200  4)  Rs.7500 
5)  None of these 
Answer : Rs.6400
Explanation :
Explanation :
Explanation:
Let the sum invested in Scheme A be Rs. x and that in Scheme B be Rs. (13900  x).
Then, (x x 14 x 2)/100 + ((13900  x) x 11 x 2) /100= 3508
28x  22x = 350800  (13900 x 22)
or 6x = 45000
or x = 7500.
So, sum invested in Scheme B = Rs. (13900  7500) = Rs. 6400.
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