5.2+Breaking+Even

LH May 5, 2009 Accentuate the Negative Big Idea Negative numbers help us to model many real world situations. Investigation 5: Coordinate Grids __ Essential Question #5: How do I multiply and divide integers? __


 * Problem 5.2 **

B) Plot the (tune-ups, profit) data from your table on a coordinate grid. Be sure to label the axis. Explain how you chose the scale for each axis. ** I chose an interval of 60 for profit, since that's the pattern and it goes up by ones for the tune-ups. C) What will Jeans profit be if she does only four tune-ups? How is this shown on the graph? ** Her profit will be -560 since she paid $800 in the beginning for her tools, but after 4 tune-ups she’s earned back $240. D) How many tune-ups will Jean have to do before she breaks even? How is this shown on the graph? ** Jean breaks-even after she has done 14 tune-ups. This is shown on the graph because at 14 she crossed over to the first quadrant where it starts to have positive numbers. E) how does Jeans profit change with each profit she does? How is this shown on the graph? ** Her profit goes up by 60 each time she does a tune-up since that’s how much she is charging for a tune-up. **__ FOLLOW UP __** P=60x10=0 The break-even point is 10. That’s when she is going to start making some profit if she does more tune-ups.
 * A) Make a table that shows the profit Jean will earn for 0 through 20 tune-ups. **
 * Tune-ups || Profit ||
 * ** 0 ** || ** -800 ** ||
 * ** 1 ** || ** -740 ** ||
 * ** 2 ** || ** -680 ** ||
 * ** 3 ** || ** -620 ** ||
 * ** 4 ** || ** -560 ** ||
 * ** 5 ** || ** -500 ** ||
 * ** 6 ** || ** -440 ** ||
 * ** 7 ** || ** -380 ** ||
 * ** 8 ** || ** -320 ** ||
 * ** 9 ** || ** -260 ** ||
 * ** 10 ** || ** -200 ** ||
 * ** 11 ** || ** -140 ** ||
 * ** 12 ** || ** -80 ** ||
 * ** 13 ** || ** -20 ** ||
 * ** 14 ** || ** 40 ** ||
 * ** 15 ** || ** 100 ** ||
 * ** 16 ** || ** 160 ** ||
 * ** 17 ** || ** 220 ** ||
 * ** 18 ** || ** 280 ** ||
 * ** 19 ** || ** 340 ** ||
 * ** 20 ** || ** 400 ** ||
 * 1. **** Jean figures out that she could decrease her start up cost to $600 by buying used tools. She writes a new equation, P=60t-600, to determine her profit. What is the break-even point for this profit equation? **

The break-even point is 20. P=60x20-1200 = 0
 * 2. **** Jean’s friend Chuck, thinks Jean should advertise her business in the local paper. This would increase her costs, giving her the profit equation P=60t-1200. What is the break-even point for this profit equation? **