Mathmetics
ISBT Mathmetics for all banking PO,Clerk,IBPS PO,Railway,SSC,IAS,OAS Exams
Q1. 

1)  72  2)  80 
3)  100  4)  120 
5)  None of these 
Answer : 100
Explanation :
Explanation :
Let, the Total Number of Students be x.
20% of Students are below 8 years of age.
The Number of Students above or equal 8 years of age =80% of x............(i)
Number of Students of 8 years of age = 48 .....(ii)
Number of Students above 8 years of age = 2/3 × Number of Students of 8 years of age.
Number of Students of 8 years of age.
Number of Students above age of 8 =2/3 × 48=32(iii)
From equation (i), (ii) and (iii),
80% of x = 48+2/3 of 48
80% of x = 80
x = 100.
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Q2. 

1)  60  2)  70 
3)  72  4)  80 
5)  None of these 
Answer : 80
Explanation :
Explanation :
Let, the total Maximum marks in exam = 100%
His score = 50% of 100 = 50
His marks after review = 140% of 50 = 70
His marks after post review = 120% of 70 = 84
A.T.Q 84% – 12 =70% + 30
14% = 42
or 100% = 300
So passing marks = 300(70/100) + 30 = 240
Total marks = 100% = 300
Thus, required percentage score needed for passing the examination = (240/300 ) X 100 = 80%
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Q3.  A vendor buy Fresh Fruits, contain 70% water and also buy Dry Fruits which contain 40% water. If he buys 120 kg of Fresh Fruits,how much quantity of Dry Fruits can be obtains from that quantity? 
1)  56 kg  2)  60 kg 
3)  64 kg  4)  72 kg 
5)  None of these 
Answer : 60 kg
Explanation : Given ,total quantity of fresh fruits = 120 kg
Explanation : Given ,total quantity of fresh fruits = 120 kg
In the fresh fruits , water contain = 120 x (70/100 ) = 84 kg and nonwater contain = 12084 = 36 kg.
In the Dry fruits, water contain = 40% and nonwater contain 60%.
Since, Nonwater quantity is always constant i.e.
60% = 36 kg
or 100% = (36/60) x 100 = 60 kg
Thus , Dry fruits quantity = 60 kg in 120 kg of Fresh fruits .
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Q4. 

1)  12.5%  2)  17.5% 
3)  19%  4)  21% 
5)  None of these 
Answer : 19%
Explanation : Allegation Method:
Explanation : Allegation Method:
10% (C) x% (D)
15% (M)
(DM) = x15 (MC) = 15 10=5
So, x15 / 5 = 4/5
or x =15+4= 19%
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Q5.  When 20% of a number added to another number, the second number increases by its 50%. what is the ratio between two numbers ? 
1)  2:5  2)  5:2 
3)  2:3  4)  3:4 
5)  None of these 
Answer : 5:2
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Q6. 

1)  425  2)  480 
3)  520  4)  625 
5)  None of these 
Answer : None of these
Explanation : Let, the full mark be 100%.
Explanation : Let, the full mark be 100%.
A boy should requires marks to pass = 483 +117 = 600
So, the full mark = 600 i.e. 100%
So, the required mark for a girl should = (600/40) x 35 = 525
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Q7. 

1)  Rs.3200  2)  Rs.3126 
3)  Rs.3136  4)  Rs.3048 
5)  None of these 
Answer : Rs.3136
Explanation :
Explanation :
Let, the total amount of money with Alok be Rs.x .
x = (504 x 100)/[100  (23+33+19+16) ]= Rs. 5600
Reqd. amount of money
= ( Rs. 5600 x 56)/100= Rs. 3136
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Q8.  A shopkeeper wants to buy 600 kg watermelon,contain 99% water. On the way of shipping due to dehydration ,it contain only 98% water when it reaches at the destination. What is the present mass of the watermelon ? 
1)  294 kg  2)  300 kg 
3)  494 kg  4)  588 kg 
5)  None of these 
Answer : 300 kg
Explanation : Given, Original weight watermelon is 600 kg .
99% water i.e. 600X99/100= 594 kg and 6 kg nonwater substance.
After, dehydration, now 98% water in new content.
But nonwater substance remain constant. In the new content, water contain 2% and nonwater contain 98%.
So, 2% = 6kg.
Or 98% = (6/2) X 98 =294 kg.
Therefore, present mass = 294+6= 300kg.
Explanation : Given, Original weight watermelon is 600 kg .
99% water i.e. 600X99/100= 594 kg and 6 kg nonwater substance.
After, dehydration, now 98% water in new content.
But nonwater substance remain constant. In the new content, water contain 2% and nonwater contain 98%.
So, 2% = 6kg.
Or 98% = (6/2) X 98 =294 kg.
Therefore, present mass = 294+6= 300kg.
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Q9.  There are 480 students in a class, consists of boys and girls, appearing in an examination. 85% of girls and 70% of boys pass in that examination. How many boys pass in the examination, if over all 75% of the students pass in that examinations ? 
1)  224  2)  216 
3)  236  4)  244 
5)  None of these 
Answer : 224
Explanation : Let, boys are x. So, girls are (480 x).
Explanation : Let, boys are x. So, girls are (480 x).
Then, 70x/100 + 85(480 x)/100 = 480 (75/100)
or (70x + 408,00  85x) = 36,000
or 15x = 4800
or x =320
So, boys pass = 320 X 70/100 = 224
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Q10.  When 30% of a number added to another number , the second number is increases by 50%.What is the ratio between the first number to second number ? 
1)  3:5  2)  5:3 
3)  2:3  4)  4:5 
5)  None of these 
Answer : 5:3
Explanation : Let, two numbers are x and y respectively.
Explanation : Let, two numbers are x and y respectively.
So, 30x/100 + y = y +50y/100
or 3x = 5y
or x:y = 5:3
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