RBQE - Units of Measure (Lesson)

Converting Units

Being able to convert between units of measure is important for your everyday life! Imagine your whipped cream recipe calls for 4 cups of cream. At the store, cream comes in pints - how many pints will you need? Well there are 2 cups in every pint, so hopefully you've realized you'll need 2 pints of cream!

Common Conversions

2 cups = 1 pint

2 pints - 1 quart

4 quarts = 1 gallon

8 fl oz = 1 cup

16 cups = 1 gallon

12 inches = 1 foot

3 feet = 1 yard

5280 feet = 1 mile

1 m = 100cm

1 cm = 10mm

1 km = 1000m

1 inch = 2.54cm

1 mile = 1.61 km

Watch this video to learn how to use fractions to convert units.

*The correct conversion for miles to km is 1.6, not 1.85*

Unit Conversion Practice

Percent & Percent Change

Percent means "hundredths" or "divided by 100". The symbol % is used to represent percent. One of the most common places we see percentages are in our grades. For instance, if you get 15 out of 20 questions correct on your test then:

$LaTeX: \frac{15}{20}=\frac{75}{100}=75\%=0.75$ $\frac{15}{20}=\frac{75}{100}=75\%=0.75$

Notice that to convert from percent to decimal, you move the decimal place twice.

Percent to decimal: 87% = 0.87 (move two places to the LEFT)
Decimal to percent: 0.93 = 93% (move two places to the RIGHT)

The quickest way to find percentages is to divide your part by your whole. For example, if you have finished 13 out of the 25 questions on your test, you divide

13/25 = 0.52 =52%

We want to be able to use percentages to solve problems, so let us translate and solve the following expressions:

1. What number is 40% of 80?

$LaTeX: x=\frac{40}{100}\cdot80\\x=0.4\cdot80\\x=32$ $x=\frac{40}{100}\cdot80\\x=0.4\cdot80\\x=32$

32 is 40% of 80.

2. What percent of 64 is 48?

$LaTeX: \frac{x}{100}\cdot64=48\\\frac{64x}{100}=48\\64x=4800\\x=75$ $\frac{x}{100}\cdot64=48\\\frac{64x}{100}=48\\64x=4800\\x=75$

75% of 64 is 48.

3. During a sale, a general store gave a 15% discount on camping chairs. How much did Ross pay for a camping chair with an original price of $50?

Two different options of an item for sale

When a price is changed, we can find the percent of increase or percent of decrease by using this formula:

changes of percent

Example: Ross went to another store and found a sleeping bag marked down from $60 to $48. Find the percent decrease of the cost of the sleeping bag.

Let x represent the percent decrease.
Find the change in the price 60 - 48 = 12
Plug into the formula: $LaTeX: \frac{x}{100}=\frac{12}{60}$ $\frac{x}{100}=\frac{12}{60}$
Cross multiply and solve: $LaTeX: 60x=1200\\x=20$ $60x=1200\\x=20$

The sleeping bag was discounted by 20%.

Watch this video for a few more examples.

Percent Problem Practice

48% of 125 is what number?
What percent of 225 is 99?
9 is 36% of what number?
What percent of 180 is 27?
Laura makes a 10.5% commission on each of her sales. How much does she make when she sells a house for $85,000?
Because an item was slightly damaged, a stock clerk reduces the price by $6. This represents a 15% reduction. What was the original price?
A $120 coat goes on sale for $96. By what percent was the coat discounted?
The Fergusons' real estate taxes went from $1560 to $1638. What was the percent of increase?
The population of Hillside High increased from 1525 students ten years ago to 1708 students last year. What was the percent of increase?

TO VIEW THE SOLUTIONS ONCE YOU HAVE PRACTICED, CLICK HERE.

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