FINDING PERCENTAGE OF A GIVEN QUANTITY

Problem 2 :

250% of 65 is what number?

Solution :

Let x be a number.

The word ‘of’ is translated as ‘multiplication’ in math.

x = (250/100) × 65

 = (16250)/100

x = 162.5

So, 250 % of 65 is162.5.

Problem 3 :

800% of 2,250 is what number?

Solution :

Let x be a number.

The word ‘of’ is translated as ‘multiplication’ in math.

x = (800/100) ×2250

 = (1800000)/100

x = 18000

So, 800 % of 2250 is18000.

Problem 4 :

A student earned a grade of 80% on a math test that had 20 problems. How many problems on this test did the student answer correctly? (round to the nearest whole number)

Solution :

Total number of problems = 20

= 80% of 20

= 0.80 (20)

= 16

So, for 16 problems he answered correctly.

Problem 5 :

There are 36 carpenters in a crew. On a certain day, 29 were present. What percent showed up for work? (round to the nearest tenth)

Solution :

Total number of carpenters = 36

Number of carpenters present = 29

Fraction part of the carpenters present = 29/36

Percentage of carpenters present = (29/36) x 100%

= 80.55%

Problem 6 :

A metal bar weighs 8.15 ounces. 93% of the bar is silver. How many ounces of silver are in the bar? (round to the nearest thousandth)

Solution :

Weight of metal bar = 8.15 ounces 

93% of the bar is silver.

93% of 8.15 = 0.93 (8.15)

= 7.57

So, 7.57 ounces of silver in the bar.

Problem 7 :

A woman put $580 into a savings account for one year. The rate of interest on the account was 6½%. How much was the interest for the year in dollars and cents? (Round to the nearest cent)

Solution :

Total savings = $580

Interest rate = 6½%

Interest = 6½% of 580

= 37.7

Problem 8 :

If 48% of the students in a certain college are female and there are 2,400 female students, what is the total number of students in the college?

Solution :

Let total number of students be x.

48% of x = 2400

(48/100) · x = 2400

x = 2400 · (100/48)

x = 5000

So, the total number of students in the college is 5000.

Problem 9 :

How much HCI (hydrochloric acid) is in a 60-milliliter bottle that is marked 80% HCI? 

Solution : 

Capacity of bottle= 60 ml

Quantity of HCL = 80% of 60

= (80/100) x 60

= 0.80 x 60

= 48 ml

So, quantity of HCL in the bottle is 48 ml.

Problem 10 :

On a 120-question test, a student got 96 correct answers. What percent of the problems did the student work correctly?

Solution :

Total number of questions = 120

Number of questions answered correctly = 95

Percentage of problems answered correctly = (96/120) x 100%

= 0.8 x 100%

= 80%

So, 80% of hte answers answered correctly.

Problem 11 :

If 25% of the students in elementary algebra courses receive a grade of A, and there are 300 students enrolled in elementary algebra this year, how many students will receive an A?

Solution :

Total number students = 300

Number of students recive grade A = 25% of 300

= (25/100) x 300

= 25 x 3

= 75 students

Problem 12 :

On a 120-question test, a student got 84 correct answers. What percent of the problems did the student work correctly?

Solution :

Total number of questions = 120

Number of questions answered correctly = 84

Percentage of students answered correctly = (84/120) x 100%

= 0.7 x 100%

= 70%

Problem 13 :

An engineering student answered 81 questions correctly on a 90-question test. What percent of the questions did she answer correctly? What percent were incorrect?

Solution :

Number of questions = 90

Number of questions answered correctly = 81

Converting into percentage, we get

= (81/90) x 100%

= 0.9 x 100%

= 90%

Problem 14 :

A basketball player made 63 out of 75 free throws. What percent is this?

Solution :

Total number of throws = 75

Number of throws made = 63

Converting into percentage = 63/75 x 100%

= (63/3) x 4%

= 21 x 4%

= 84 %

So, 84% of balls made it.