Estimating Percents

E8.5 - LA1 - Multi-step percent problems and Estimating Tips

Example: A video game originally cost $100. The game is on sale for 40% off and you will need to pay 9% sales tax. How much will you pay in total.

• Calculate the discount  $100\ \cdot\ \frac{40}{100}=40$  

• Calculate the discounted price  $100 - $40 = $60

• Calculate the sales tax  $60\cdot\frac{9}{100}=\ \text{5.40}$  

• Add the sales tax to the sales price:  $5.40 + $60 = $65.40

Example: ALTERNATE METHOD - A video game originally cost $100. The game is on sale for 40% off and you will need to pay 9% sales tax. How much will you pay in total.

• Calculate the discounted price $100\ \left(1\ -\ 0.4\right)=100\left(0.6\right)\ =\ 60$  

• Calculate the total price with 9% tax  $60\left(1+.09\right)=65.40$  

Multiple Choice

A video game originally cost $100. It is on sale for 70% off and sales tax is 9%. What is the total cost you would have to pay for the game (including the discount and tax)?

• $76.30

• $70

• $30

• $32.70

Multiple Choice

A video game originally cost $50. It is on sale for 60% off and sales tax is 9%. What is the total cost you would have to pay for the game (including the discount and tax)?

• $20

• $21.80

• $30

• $32.70

Estimate Tips

• Read the question!!!!!

• Each question will tell you which place value to round to.

• Remember if the digit after that place value is 5 or higher round up, less than 5 round down.

• Example: Bill amount $46.20

• Rounding to the nearest dollar would be $46 (because 2 is less than 5)

• Rounding to the nearest ten dollars would be $50 (because 6 is greater than 5)

Estimate Tips

• Example: Bill amount $46.20

• Rounding to the nearest dollar would be $46 (because 2 is less than 5)

• Multiply $46 by 20% = $9.2

• or Double and use 1 decimal place = $9.2

• 
  

Estimate Tips

• Example: Bill amount $46.20

• Rounding to the nearest ten dollars would be $50 (because 6 is greater than 5)

• Multiply $50 by 20% = $10

• or Double and use 1 decimal place = $10.0

• 
  

Multiple Choice

Your dinner bill is $24.90.

Estimate a 20% tip based on rounding to the nearest dollar.

• $4.80

• $5.00

• $4.00

• $6.00

Multiple Choice

Your dinner bill is $24.90.

Estimate a 20% tip based on rounding to the nearest ten dollars.

• $4.80

• $5.00

• $4.00

• $6.00