Sign In | Subscribe
Start learning today, and be successful in your academic & professional career. Start Today!
Loading video...
This is a quick preview of the lesson. For full access, please Log In or Sign up.
For more information, please see full course syllabus of Pre Algebra
  • Discussion

  • Study Guides

  • Practice Questions

  • Download Lecture Slides

  • Table of Contents

  • Related Books

Bookmark and Share
Lecture Comments (17)

1 answer

Last reply by: Professor Fung
Sat Jul 20, 2013 1:32 AM

Post by James Reynolds on July 17, 2013

I agree, the videos are very good moreover and I'm grateful for the resource.

It seems that N Fung worked out 175/105 rather than 105/175.

I bet plenty of engineers have made that mistake before.

2 answers

Last reply by: Catherine Buffington
Thu Sep 6, 2012 7:42 PM

Post by Valdo Ribeiro on December 15, 2011

This errors are the point.
The more you see the more you understand, and please, lets pay some respect to our Professors!
Im a Structural Engineer and im enjoying this videos.Remember the basis of learnig is recognizing your place!

1 answer

Last reply by: Catherine Buffington
Thu Sep 6, 2012 7:45 PM

Post by javier mancha on September 16, 2011

I have to find Two-ninths of 36 , how do i work that equation out ? please

2 answers

Last reply by: Catherine Buffington
Thu Sep 6, 2012 7:40 PM

Post by Eliezer Rietti on January 6, 2011

If the number following the word 'of' is the denominator, than shouldn't the question "what percent of 115 is 46" mean 46/115, not 115/46?

4 answers

Last reply by: Professor Fung
Sat Jul 20, 2013 1:26 AM

Post by Tyrone Dack on September 22, 2010

What percent of 175 is 105? How is 105 166.666% of 175..when it is much less. These videos are confusing me

1 answer

Last reply by: Catherine Buffington
Thu Sep 6, 2012 7:37 PM

Post by Tyrone Dack on September 22, 2010

65% of 143 is 92.95? Not 83.95 like in the video?

Percents and Proportions

  • Percent represents a part of a whole. Remember to ask yourself if your answer makes sense. For example 50% of 120 means half of 120; 150% of 120 means over 120, in fact 120 plus an additional half.
  • You can use a proportion to solve a percent problem. Set a ratio equal to an unknown out of 100.
  • The number that follows the word “of” is the denominator.

Percents and Proportions

Find 45% of 82.
  • [x/82] = [45/100]
  • 100x = 45 ×82
  • 100x = 3690
  • x = 3690 ÷100
x = 36.9
Find 60% of 29.
  • 0.60 ×29 =
17.4
Find 48% of 102.
  • [48/100] = [x/102]
  • 100x = 8 ×102
  • 100x = 4896
  • x = 4896 ÷100
x = 48.96
What percent of 1030 is 845 to the nearest hundredth?
  • [1030/845] =
  • 1.2189 ×100% =
121.89%
What percent of 87 is 194 to the nearest hundredth?
  • [87/194] =
  • 0.4485 ×100%
44.85%
To the nearest hundredth, 10 is 45% of what number?
  • [10/x] = [45/100]
  • 45x = 1,000
x = 22.22
To the nearest hundredth, 94 is 85% of what number?
  • [94/x] = [85/100]
  • 85x = 9,400
x = 110.59
There are 800 students in the astronomy class at a university. This makes up 20% of the students at the school. How many students are at the university?
  • [800/x] = [20/100]
  • 17x = 80,000
x = 4000 students
Veronica used 75 feet of her roll of fabric. There is still 85% left of the roll. To the nearest hundredth, how long was the roll of fabric before Veronica used it?
  • [75/x] = [85/100]
  • 85x = 7,500
x = 88.24 feet
California is 163,969 square miles, which is about 4.3% the size of the United States. To the nearest square mile, how big is the United States?
  • [163,696/x] = [4.3/100]
  • 4.3x = 16,369,600
x = 3,806,883 square miles

*These practice questions are only helpful when you work on them offline on a piece of paper and then use the solution steps function to check your answer.

Answer

Percents and Proportions

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • What You'll Learn and Why 0:05
    • Topics Overview
  • Vocabulary 0:23
    • Proportion
    • Cross Products
  • Finding Part of a Whole 1:07
    • Method 1: Find 50% of 36
    • Method 2: Find 50% of 36
  • Finding Part of a Whole, cont. 3:06
    • Example: Find 65% of 143
  • Finding the Whole Amount 3:44
    • Example: How Many Students are in 8th Grade?
  • Finding the Whole Amount, cont. 5:18
    • Example: How Many Students are in the School?
  • Finding a Percent 6:38
    • Method 1: What Percent of 175 is 105
    • Method 2: What Percent of 175 is 105
  • Finding a Percent, cont. 9:57
    • What Percent of 115 is 46?
  • Extra Example 1: Find 8% of 48 11:09
  • Extra Example 2: 9 is 25% of What Number? 11:34
  • Extra Example 3: How Many Students are in the Class? 12:39
  • Extra Example 4: 66 is What Percent of 55? 14:25