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Q:

The sum of the number of boys and girls in a school is 150. if the number of boys is x, then the number of girls becomes x% of the total number of students. The number of boys is : 

A) 60 B) 70
C) 80 D) 90
 
Answer & Explanation Answer: A) 60

Explanation:

We have : x + (x% of 150 )= 150 

=> x+(x/100)*150] = 150

=> 52x = 150  

=> x = (150*2)/5 = 60

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Q:

If 20% of a = b, then b% of 20 is the same as :

A) 4% of a B) 6% of a
C) 8% of a D) 10% of a
 
Answer & Explanation Answer: A) 4% of a

Explanation:

20% of a = b 

=> (20/100) * a = b 

 b% of 20 =(b/100) x 20 = [(20a/100)  / 100] x 20= 4a/100 = 4% of a.

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Filed Under: Percentage
Exam Prep: CAT , Bank Exams , AIEEE
Job Role: Bank PO , Bank Clerk , Analyst

Q:

The value of a machine depreciates at the rate of 10% every year. It was purchased 3 years ago. If its present value is Rs. 8748, its purchase price was :

A) 10000 B) 12000
C) 14000 D) 16000
 
Answer & Explanation Answer: B) 12000

Explanation:

Purchase price = Rs.87481-101003 = Rs. [8748 * (10/9) * (10/9 )* (10/9)] = Rs.12000

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Q:

 The difference between a number and its two-fifth is 510. What is 10% of that number ?

A) 75 B) 85
C) 95 D) 105
 
Answer & Explanation Answer: B) 85

Explanation:

Let the number be x. Then, x-(2/5)x = 510

=> 3x/5 =510 

=>x =[510 * ( 5/3)] =850 

10 % 0f 850 = 85.

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Q:

A student multiplied a number by 3/5 instead of 5/3, What is the percentage error in the calculation ?

A) 54 % B) 64 %
C) 74 % D) 84 %
 
Answer & Explanation Answer: B) 64 %

Explanation:

Let the number be x.

Then, ideally he should have multiplied by  x by 5/3. Hence Correct result was x * (5/3)= 5x/3. 

 

By mistake he multiplied x by 3/5 . Hence the result with error  = 3x/5 

Then, error = (5x/3 - 3x/5) = 16x/15 

Error %  = (error/True vaue) * 100 = [(16/15) * x/(5/3) * x] * 100 = 64 %

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Q:

What percent decrease in salaries would exactly cancel out the 20 percent increase ?

A) (16 + 2/3) % B) (15 + 2/3)%
C) (14 +1/3)% D) (13 + 4/5)%
 
Answer & Explanation Answer: A) (16 + 2/3) %

Explanation:

Let the orginal salary = Rs. 100. New's salary = Rs.120.

Decrease on 120 = 20. Decrease on 100 = [(20/120)*100]% = (16 + 2/3) %. 

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Q:

In a City, 35% of the population is composed of migrants, 20% of whom are from rural areas. Of the local population, 48% is female while this figure for rural and urban migrants is 30% and 40% respectively. If the total population of the city is 728400, what is its female population ?

A) 324138 B) 349680
C) 509940 D) None of these
 
Answer & Explanation Answer: A) 324138

Explanation:

Total Population = 728400

 

Migrants = 35 % of 728400  =  254940

 

local population = (728400 - 254940) = 473460.

 

Rural migrants = 20% of 254940 = 50988

 

Urban migrants = (254940 - 50988) = 203952

 

Female population = 48% of 473460 + 30% of 50988 + 40% of 203952 = 324138                        

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Filed Under: Percentage

Q:

If x is 80% of y, then what percent of 2x is y?

A) 65.5 % B) 64.5 %
C) 63.5 % D) 62.5 %
 
Answer & Explanation Answer: D) 62.5 %

Explanation:

 x = 80 % of y  

=> x =(80/100 )y  

=> y/x = 5/4  

Required percentage =  [(y/2x)*100] % = (5/8*100) % =62.5%

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Filed Under: Percentage