Make a scatter plot to determine the relationship between the data. Then, find the equation of the line of best fit for the given data.
6 hours
Practice makes perfect
The given table shows the numbers of hours a waitress works and the how much she earns in tips. We want to find the number of hours we would expect her to work when she earns $42 in tips. Consider the given table.
Hours Worked, x
2
5.5
1
7
2.5
8
3
5
Tips (dollars), y
15
40
7
50
18
55
20
36
We will start by making a scatter plot showing our data. This will let us determine the relationship between the data.
The points appear to lie close to a straight line, which suggests that there is a linear relationship between the data. Let's use a graphing calculator to help us find the equation of a line of best fit to help us find the information we want. First, we enter the values into lists. Push STAT, choose Edit, and then enter the given values in the first two columns.
Next, to display an equation of the line of best fit, we press STAT, scroll to right to view the CALC options, and then choose the fourth option in the list, LinReg.
Now we can write an equation of the best fit for our data. Let's round the coefficient and constant to one decimal place for simplicity.
y=7x+0.4
We can use this equation to estimate the number of hours we expect the waitress to work in order to earn $42 in tips if we substitute 42 for y in our equation and solve for x. Let's do it!
