Question

At many bakeries, there are deals that if you buy twelve donuts, you get a thirteenth one at a discount. Sometimes "13" items is called a baker's dozen. I One store is advertising: Donuts! $1.05 individually, or $13 per baker's dozen. They want to program their cash register to be able to show the exact price for any number of donuts. You will help them by producing a data table, a graph and an algorithm. You will: 1. Fill in and expand the data table 2. Make a scatter plot to show the pattern visually. This means to plot an (x,y) point for every row in the data table. For example the first point can be (1, 1.05) 3. Develop an algorithm to find the cost for any number of donuts. Note: An algorithm is like a set of instructions to solve a problem. They are useful for telling computers or people exactly how to do something. For example, here is an algorithm that finds 15% of a number: Step 1: take any number, callit N.

Answer 1

Table

Number of donuts Price

1 $1.05

2 $ 2.1

3 $3.15

4 $4.2

5 $5.25

6 $6.3

10 $10.5

slope = (10.5 - 1.05) / 10 - 1

= 9.45 / 9

= 1.05

Equation

y - 10.5 = 1.05 (x - 10)

y = 1.05x - 10.5 + 10.5

y = 1.05x

For 40 donuts

y = 1.05(40)

y = $42