Holt CA Course Estimating with Percents NS1.4 Calculate given percentages of quantities and solve problems involving discounts at sales, interest earned, and tips. Also covered: NS2.1 California Standards

Holt CA Course Estimating with Percents The table shows common percents and their fraction equivalents. You can estimate a percent of a number by substituting a fraction that is close to a given percent. Fraction Percent 10%20%25%50%33 % %

Holt CA Course Estimating with Percents Use a fraction to estimate 27% of 63. Additional Example 1: Using Fractions to Estimate Percents 27% of 63  1414  63  1414  60  15 27% of 63 is about 15. Compatible numbers are close to the numbers in the problem and help you use mental math to find a solution. Remember! Think: 27% is about 25% and 25% is equivalent to Change 63 to a compatible number. Multiply.

Holt CA Course Estimating with Percents Use a fraction to estimate 48% of 91. Check It Out! Example 1 48% of 91  1212  91  1212  90  45 48% of 91 is about 45. Think: 48% is about 50% and 50% is equivalent to Change 91 to a compatible number. Multiply.

Holt CA Course Estimating with Percents Tara’s T’s is offering 2 T-shirts for $16, while Good-T’s is running their buy one for $9.99, get one for 50% off sale. Which store offers the better deal? Additional Example 2: Consumer Math Application First find the discount price for 2 t-shirts at Good T’s. 50% of $9.99 = 1212  $9.99  1212  $10  $5 The second shirt cost approximately $5. Since $10 + $5 = $15, the 2 T-shirts for $15 at Good-T’s is the better deal. Think: 50% is equivalent to. 1 2 Change $9.99 to a compatible number. Multiply.

Holt CA Course Estimating with Percents Check It Out! Example 2 First find the discount on the notebook at Billy’s Office Supply. 25% of $9.75 = 1414  $9.75  1414  $10  $2.50 The discount is approximately $2.50. Since $10 – $2.50 = $7.50, the notebook from K’s Office Supply Store is the better deal. Think: 25% is equivalent to. 1 4 Change $9.75 to a compatible number. Multiply. Billy’s Office Supply Store is offering 25% off a leather notebook, originally priced at $9.75. K’s Office Supply Store offers the same notebook, not on sale, at $7.00. Which store offers the better deal?

Holt CA Course Estimating with Percents Another way to estimate percents is to find 1% or 10% of a number. You can do this by moving the decimal point in the number. 1% of 45 =10% of 45 = To find 1% of a number, move the decimal point two places to the left. To find 10% of a number, move the decimal point one place to the left

Holt CA Course Estimating with Percents Use 1% or 10% to estimate the percent of each number. Additional Example 3: Estimating with Simple Percents A. 4% of is about 20, so find 4% of 20. 1% of 20 = 20. 4% of 20 = 4  0.2 = 0.8 4% of 18 is about % equals 4 · 1%..

Holt CA Course Estimating with Percents Use 1% or 10% to estimate the percent of each number. Additional Example 3: Estimating with Simple Percents B. 29% of 80 29% is about 30, so find 30% of % of 80 = % of 80 = 3  8.0 = % of 80 is about % equals 3 · 10%..

Holt CA Course Estimating with Percents Use 1% or 10% to estimate the percent of each number. Check It Out! Example 3 A. 5% of is about 15, so find 5% of 15. 1% of 15 = 15. 5% of 15 = 5  0.15 = % of 14 is about % equals 5 · 1%..

Holt CA Course Estimating with Percents Use 1% or 10% to estimate the percent of each number. Check It Out! Example 3 B. 21% of 60 21% is about 20, so find 20% of % of 60 = % of 60 = 2  6.0 = % of 60 is about % equals 2 · 10%..

Holt CA Course Estimating with Percents Tim spent $58 on dinner for his family. About how much money should he leave for a 15% tip? Additional Example 4: Consumer Math Application Since $58 is about $60, find 15% of $60. 15% = 10% + 5% 10% of $60 = $6 5% of $60 = $6 ÷ 2 = $3 $6 + $3 = $9 Tim should leave about $9 for a 15% tip. Think: 15% is 10% + 5%. 5% is of 10% so divide $6 by Add the 10% and 5% estimates.

Holt CA Course Estimating with Percents Amanda spent $12 on a hair cut. About how much money should she leave for a 15% tip? Check It Out! Example 4 Since $12 is about $10, find 15% of $10. 15% = 10% + 5% 10% of $10 = $1 5% of $10 = $1 ÷ 2 = $0.50 $1 + $0.50 = $1.50 Amanda should leave about $1.50 for a 15% tip. Think: 15% is 10% + 5%. 5% is of 10% so divide $1 by Add the 10% and 5% estimates.