Question

The table of values below represents a linear function and shows the amount of money in a tip jar at a dry cleaners since the dry cleaners opened for the day. How much was in the tip jar when the dry cleaners opened?

Answer 1

4.50

Explanation:

from the table, we can tell the tip increases by 2.75 per hour

the 3rd hour: 15.50-2.75=12.75

the second hour: 12.75-2.75=10.00

the 1st hour: 10.00-2.75=7.25

the 0 hour: 7.25-2.75=4.50

so there was 4.50 in the jar

Answer 2

A linear equation has a standard form of:

y = mx + b

where in this case,

y = amount of money in tip jar, m = slope, x = number of hours, b = y intercept

We select any two paired data to calculate for the slope:

m = (y2 – y1) / (x2 – x1)

m = (18.25 – 15.50) / (5 – 4)

m = 2.75

y = 2.75x + b

Choosing any one data pair to calculate for b the y-intercept:

15.50 = 2.75 (4) + b

b = 4.5

Therefore there was $4.50 in the tip jar during the opening.

Answer: $4.50