standard_description: Develop a probability model and use it to find probabilities of events. Compare probabilities from a model to observed frequencies; if the agreement is not good, explain possible sources of the discrepancy.
problem_activity: Problem 1
For Simon’s birthday, he and his family go out to eat at a restaurant.
a.   The amount of tax is $3.40, which is 5% of the food bill. How much was the food bill not including the tax?
b.   If Simon wants to leave a 20% tip on the amount of the food bill before tax, how much should he leave for a tip?
c.   What is Simon’s total bill including tax and tip? What percent of the food bill is this?
Problem 2
Emily has a coupon for 20 percent off of her purchase at the store. She finds a backpack that she likes on the discount rack. Its original price is $60, but everything on the rack comes with a 30 percent discount.
Emily says, “
Thirty percent and twenty percent make fifty percent, so it will cost $30.
”
Is Emily correct? Explain your reasoning. In your explanation, if you disagree with Emily, find the price she will pay for the backpack.
Problem 3
In order to make money, a store marks up its prices by 25% from the warehouse prices. Let
$$p$$
represent the price at which the store gets its merchandise from the warehouse, and let
$$s$$
represent the price the store sells the merchandise for after the markup.
a.   Write an equation to determine the selling price,
$$s$$
, based on the warehouse purchase price,
$$p$$
.
b.   Create a table showing possible pairs of solutions to the equation.
{"table": [{"_attributes": {"align": "Center", "class": ["table", "table-bordered"], "style": "width:50%"}, "tbody": [{"tr": [{"td": [{"_attributes": {"style": "background-color:#eeeeee; text-align:center"}, "strong": [{"span": [{"_attributes": {"class": ["math-tex"]}, "_value": "$$p$$"}], "_values": ["Warehouse price (", ")"]}]}, {"_attributes": {"style": "background-color:#eeeeee; text-align:center"}, "strong": [{"span": [{"_attributes": {"class": ["math-tex"]}, "_value": "$$s$$"}], "_values": ["Selling price (", ")"]}]}]}, {"td": [{}, {}]}, {"td": [{}, {}]}, {"td": [{}, {}]}, {"td": [{}, {}]}]}]}]}
c.   Create and label a graph for your table.
d.   Interpret the points
$$(0, 0)$$
and
$$(1, r) $$
from the graph in context of the situation.


aligns: no