Lesson 4

You have seen that the line of best fit identifies a trend in data but the line does not necessarily include all points. The situation in Self-Check 1 gives a more exact line of best fit. Now check your skills in Self-Check 1.

 

Self-Check 1

 

The amount of money spent on gas is related to the number of litres purchased. The following chart shows amounts of gas purchased.

 

Litres (L)	10	20	30	40	50
Cost ($)	11.20	22.40	33.60	44.80	56.00

1. Is this a direct linear relation or a partial linear relation? Explain. Answer
2. Should the points be connected? Answer
3. What is the cost per litre? Answer
4. Determine the equation that relates the data in the relation above. Answer

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From your work and checked answers in Self-Check 1, you should feel comfortable in attempting Try This 4.

 

Try This 4

 

A professional photographer charges $75 for a sitting fee and an additional $12.50 for each portrait taken.

1. Find an equation that relates the total cost to the sitting fee and to the number of portraits taken.
2. Using the equation, how much would it cost for 14 portraits?
3. How much would it cost to get an individual portrait for each student in a graduating class of 350 people? The students will share one sitting.
4. How many individual portraits are taken if the total cost is $2725 and only one sitting fee is paid?

Save your responses in your course folder.