8.4 Consumer Applications

SOL

The student will solve practical problems involving consumer applications.

Essential Knowledge

The "Consumer Applications" unit is broken up into several "sub-units": rates, tax-tip-discount-markup, percent change, simple interest (loans, savings accounts, commission), and checkbooks.

• Background knowledge:

  • Percent: a comparison by breaking something into 100 parts. Per-cent literally means "out of 100.)

  • Proportion: a way of comparing 2 ratios (fractions) that are equal. If you know 3 of the amounts, you can figure out the 4th amount.

• Rates:

  • Ratio: a comparison of 2 amounts. Part/part, part/whole, and whole/part are most common types we use.

  • Rate: a ratio of home much of one thing compared to how much of something else; they do not have to be related (e.g., miles per tank of gas).

  • Unit Rate: a ratio of how much of one thing compared to a single item of something else; they do not have to be related (e.g., miles per gallon on a given trip).

• Percent change (including tax, tip, discount, markup, & commission):

  • Subtotal: the sum of all items & prices before tax or tip is added.

  • Sales Tax: a percentage of the subtotal that is added.

  • Tip: a percentage of the bill that is added as a "thank you" for service (standard is 20%).

  • Original Price: the selling price of an item before any discounts are taken off.

  • Discount Rate: the percentage of a price by which an item is reduced.

  • Discount Amount: the dollar amount that an original price is reduced to get the sale price.

  • Sale Price: the price of an item after an original price is reduced by a discount.

  • Wholesale Price: how much a store pays for an item.

  • Markup: how much a store increases the price of an item (they do this to make money).

  • Selling Price: how much an item is sold for after a markup is applied.

  • Percent change (increase / decrease): the percentage change of an amount compared to what it started as.

• Loans, savings accounts, & commission:

  • Loan: an amount of money borrowed.

  • Savings Account: money placed in account to earn interest.

  • Principal: the initial (starting) amount that is borrowed (for a loan) or deposited (in a savings account).

  • Term: how long the loan / savings account is for; this amount is always in years.

  • Interest Rate: a percentage of a loan that is charged for the privilege of borrowing the money. Also, a percentage of a savings account that is offered as a reward for maintaining a certain amount.

  • Interest: how much money is actually charged for a loan OR how much money is added to the principal in a savings account.

  • Simple Interest: an introductory way of calculating interest for a loan or savings account where interest is only added to the principal.

  • Commission: a bonus received for selling items; based on a percentage of the sales.

• Checkbooks:

  • Checking Account: an account with a bank where money is kept to be used to make purchases.

  • Balance: the current amount in a checking account.

  • Transaction: any action taking place with a checking account (e.g., deposit, debit, withdrawal).

  • Checkbook: a tool used to keep track of transactions.

  • Reconcile: when a checkbook is used to play "catch-up" with the account balance after several transactions.

  • Debit: when a purchase is made with a card linked to the checking account (decreases the balance).

  • Deposit: when money is put into an account (increases the balance)

  • Withdrawal: when money is directly taken out of an account (decreases the balance).

Target Skills

• Solve practical (real-world) problems using proportional reasoning and calculations using rational numbers.

• Balance a checkbook with up to 5 transactions (debits, withdrawals, deposits).

• Calculate a discount or markup and the resulting selling price.

• Calculate sales tax or tip and the resulting total.

• Calculate simple interest for a loan/savings account.

  • Be able to figure out the total amount repaid/balance.

• Determine the percent change (increase / decrease) for a practical problem.

Desmos Tips

IXL Topics

Rates, Ratios, Proportions

• 6.R.1-13

• 7.J.1-6, 9-16

• 7.K.1-11

• 8.H.1-13

• 8.I.1-10

• A.C.1-7

Percents

• 6.S.5-10

• 7.L.1-11

• 8.J.1-12

• A.D.1-9

Consumer Math

• 6.V.1-8

• 7.M.1-12

• 8.K.1-10

Websites (Videos)

Websites (Practice)

Websites (Games)