PERCENTS WORKSHEET

Problem 1 :

Find 24% of 20.

Problem 2 :

What percent of 80 is 20?

Problem 3 :

88 is what % of 160?

Problem 4 :

30% of what number is 21?

Problem 5 :

50 is 0.4% of what number?

Problem 6 :

The price of a product is increased from $90 to $108. Find the percent increase.

Problem 7 :

In a library there are 1500 books in which 1125 are English books and the rest are Spanish books. Find the percent of Spanish books in the library.

Problem 8 :

A product is sold at 10% discount and there is 5% sales tax on the discounted price. If a customer pays $113.40 for the product, find its original.

Problem 9 :

Jewelers use the karat system to determine the amount of pure gold in jewelry. Pure gold is 24 karat, meaning the item is 100% gold. A 14.4-karat gold ring contains 14.4 parts gold and 9.6 parts other metal. What percent of the ring is gold?

Problem 10 :

A chemist has 20 milliliters of a solution that is 40% acid. She wants to increase the acid content of the solution to make it a 50% acid solution. How many milliliters of pure acid should she add to the solution?

Problem 11 :

In the first 20 days of a month, a sales man has made $2,550 sales which is 85% of his monthly target. Find the monthly target.

Problem 12 :

A student has scored 450 marks which 45 marks more than the pass marks. If each student has to secure 45% of the total marks to pass the exam, find the total marks in the exam.

Answers

1. Answer :

24% of 20 :

= (²⁴⁄₁₀₀)(20)

= 0.24(20)

= 4.8

2. Answer :

Let x percent of 80 be 20.

x% of 80 = 20

(ˣ⁄₁₀₀)80 = 20

⁴ˣ⁄₅ = 20

Multiply both sides by 5.

4x = 100

Divide both sides by 4.

x = 25

Therefore, 25 percent of 80 is 20.

3. Answer :

Let 88 be x% of 160.

88 = x% of 160

88 = (ˣ⁄₁₀₀)160

88 = ⁸ˣ⁄₅

Multiply both sides by 5.

440 = 8x

Divide both sides by 8.

x = 55

Therefore, 88 is what 55% of 160.

4. Answer :

Let 30% of x be 21.

30% of x = 21

(³⁰⁄₁₀₀)x = 21

(³⁄₁₀)x = 21

Multiply both sides by 10.

3x = 210

Divide both sides by 3.

x = 70

Therefore, 30% of 70 is 21.

5. Answer :

Let 50 be 0.4% of x.

50 = 0.4% of x

50 = (.⁴⁄₁₀₀)x

Multiply both sides by 100.

5000 = 0.4x

Divide both sides by 0.4.

12,500 = x

Therefore, 50 is 0.4% of 12,500.

6. Answer :

Percent increase :

= 20%

7. Answer :

Total number of books = 1500

Number of English books = 1125

Number of Spanish books :

= 1500 - 1125

= 375

Percent of spanish books in the library :

= 25%

8. Answer :

Let x be the original price of the product.

After 10% discount, the price of the product :

= (100 - 10)% of x

= 90% of x

= 0.9x

After 5% sales tax on the discounted price, the price of the product :

= (100 + 5)% of 0.9x

= 105% of 0.9x

= 1.05(0.9x)

= 0.945x

Given : After 10% discount 5% sales tax on the discounted price, a customer pays $113.40 for the product.

0.945x = 113.40

Divide both sides by 0.945.

x = 120

Therefore, original price of the product is $120.

9. Answer :

Given : A 14.4-karat gold ring contains 14.4 parts gold and 9.6 parts other metal.

Percent of gold in the ring :

= 60%

10. Answer :

Amount of acid in 20 milliliters of a solution that is 40% acid :

= 40% of 20

= 0.4(20)

= 8 milliliters

Let x milliliters of pure acid should be added to 20 milliliters to get a 50% acid solution.

Now, amount of acid in the resulting solution :

= (8 + x) milliliters

Given : Resulting solution is a 50% acid solution.

8 + x = 50% of (20 + x)

8 + x = 0.5(20 + x)

8 + x = 10 + 0.5x

0.5x = 2

x = 4

Therefore, the chemist should add 4 milliliters of pure acid to make it a 50% acid solution.

11. Answer :

Let x be the monthly target.

Given : 85% of the monthly target is $2,550.

85% of x = 2550

0.85x = 2550

x = 3000

Therefore, the monthly target is $3,000.

12. Answer :

Let x be the total marks in the exam.

Given : 450 marks is 45 marks more than the pass marks and a student has to secure 45% of the total marks to pass the exam.

45% of x = 450 - 45

0.45x = 405

x = 900

The total marks in the exam is 900.

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