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Percentage Questions and Answers

Percentage - Aptitude

11.Sixty five percent of a number is 21 less than four-fifth of that number.What is the number?

A. 138

B. 140

C. 144

D. 149

x

 

Option: B

Explanation

consider the number as x

65% of x is 21 less than 4/5 of x

i.e) 4/5 of x - 65% of x = 21

convert percentage into fractions

4/5x - 65/100x = 21

taking LCM

(80x - 65x)/100 = 21

15x = 21 * 100

x = 2100/15 = 140

Ans = 140

Answer


12.Difference of two numbers is 1660. If 7.5% of one number is 12.5% of the other number, find the two numbers.

A. 2490, 4150

B. 2490, 4250

C. 2400, 4100

D. 2450. 4000

x

 

Option: A

Explanation

consider the two numbers as x and y

Difference of two numbers is 1600

i.e) x - y = 1660

we can also say 7.5% of x = 12.5% of y

convert percentage into fractions

(7.5/100) * (1/10) * x = (12.5/100) * (1/10) * y

75/100x = 125/100y

75x = 125y

x = 125y/75 = 5y/3

we know that, x - y = 1660, substitute the value of x in here

5y/3 - y = 1660

(5y - 3y)/3 = 1660

y = (1660 * 3)/2 = 2490

i.e) x - 2490 = 1660

x = 1660 + 2490 = 4150

Ans = Two numbers are 2490 & 4150

Answer


13.In expressing a length 81.472km as nearly as possible with three significant digits, find the percentage error.

A. 0.034%

B. 0.04%

C. 0.048%

D. 0.05%

x

 

Option: A

Explanation

error = (81.5 - 81.472)km = 0.028

To find percentage error

((0.028/81.472) * 100) %= 0.034%

Ans = 0.034%

Answer


14.In an election between two candidates, 75% of the voters cast their votes,out of which 2% of the votes were declared invalid. A candidate got 9261 votes which were 75% of the total valid votes. Find the total number of votes enrolled in that election.

A. 18000

B. 14900

C. 15600

D. 16800

x

 

Option: D

Explanation

consider the total number of votes enrolled as x

so number of votes cast = 75% of x

also valid votes = 98% of(75% of x)

A candidate got 9261 votes which is 75% of valid votes

i.e) 75% of(98% of (75% of x)) = 9261

convert percentage into fractions

(75/100) * (98/100) * (75/100) * x = 9261

x = (9261 * 100 * 100 * 100)/(75 * 98 * 75) = 16800

Ans = 16800 votes

Answer


15.Raja's Mathematics test had 75 problems i.e) 10 arithmetic, 30 algebra and 35 geometry problems. Although he answered 70% of the arithmetic, 40% of the algebra and 60% of the geometry problems correctly, he did not pass the test because he got less than 60% of the problems right. How many more questions he would have needed to answer correctly to earn a 60% passing grade?

A. 2

B. 4

C. 5

D. 6

x

 

Option: C

Explanation

number of questions attempted correctly=(70% of 10 + 40% of 30 + 60% of 35)

convert percentage into fractions

((70/100) * 10) + ((40/100) * 30) + ((60/100) * 35)

7 + 12 + 21 = 40

number of questions answered correctly by raja is 40 questions

Questions to be answered correctly for 60% grade = 60% of 75

convert percentage into fractions

(60/100) * 75 = 45 questions

required number of questions = (45 - 40) = 5 questions

Ans = 5 questions

Answer


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