Fractions, Decimals, and Percents Parts of the whole

Percent comes from the Latin per centum, or “per hundred” Consequently, a number such as 32% can be written as “32 per hundred” or the fraction 32/100. This fraction is equivalent to the decimal Percent – is a ratio of a number to 100. What’s the etymology of the word “percent”?

The word “percent” meaning “per hundred” is used to show parts of a whole, the same as a fraction is used to represent part of a whole. If you had a pizza that was cut into 100 pieces, 25% of the pizza would be 25 pieces!

You Try: Write the following percents as fractions 72% 45.8% 3% 0.12%

Fraction to percent Multiply the number by 100, reduce and attach a percent (%) sign.

You Try: Write the following fractions as percents

Fraction to Decimal Divide the denominator (the bottom of the fraction) into the numerator (the top of the fraction). Place a decimal after the number inside the division “box” and attach as many zeros as necessary to complete the division. If the quotient does not come out evenly, follow the rules for “rounding off” numbers. numerator denominator

You Try: Write the following fractions as decimals using long division

Decimal to percent.50 = 50% (0.50 x 100 = 50.0) Attach the % sign Move the decimal point two (2) places to the right (this multiplies the number by 100)

You Try: Write the following decimals as percents (Remember: 1.0 is 100% when written as a percent)

Decimal to fraction You will be using place value to do this! Count the decimal places of the decimal starting from the decimal point. If there is one decimal point, place the number over 10 and reduce. If there are two decimal places, place the number over 100, and reduce. If there are three decimal places, place the number over 1000, and reduce…Etc. (This is really just using your knowledge of place value to name the denominator.) 1 decimal place = tenths, 2 decimal places = hundredths, 3 decimal places = thousandths SKIP!!!!!!!

Percent to decimal 50% = ÷ 100 =.50 Move the decimal point two (2) places to the left (this divides the number by 100)

You Try: Convert the following percents to decimals 72% 45.8% 3% 0.12%

In Conclusion FractionsDecimalsPercents 72/ % 45.8/ % 3/ %.12/ %

Problem Solving with Percents

There are three types of percent problems: 1) finding a percent of a number, 2) finding a number when a percent of it is known, and 3) finding the percent when the part and whole are known 1) what is 60% of 30? 2) what number is 25% of 160? 3) 45 is what percent of 90?

Solving Equations Containing Percents Most percent problems are word problems and deal with data. Percents are used to describe relationships or compare a part to a whole. Sloths may seen lazy, but their extremely slow movement helps make them almost invisible to predators. Sloths sleep an average of 16.5 hours per day. What percent of the day do they sleep? Solution

Equation Method What percent of 24 is n · 24 = 16.5 n = n = 68.75% Proportional method Part Whole

Solve the following percent problems 1) 27 is what percent of 30? 2) 45 is 20% of what number? 3) What percent of 80 is 10? 4) 12 is what percent of 19? 5) 18 is 15% of what number? 6) 27 is what percent of 30? 7) 20% of 40 is what number? 8) 4 is what percent of 5?

9) The warehouse of the Alpha Distribution Company measures 450 feet by 300 feet. If 65% of the floor space is covered, how many square feet are NOT covered? 10) A computer that normally costs $ is on sale for 30% off. If the sales tax is 7%, what will be the total cost of the computer? Round to the nearest dollar. 11) Teddy saved $63.00 when he bought a CD player on sale at his local electronics store. If the sale price is 35% off the regular price, what was the regular price of the CD player?