4.1+Paying+in+Installments+10-11

Ariyana Chowdhury Block H- Math May 30th 2011



= Big Idea: Many real world problems and situations can be modeled using mathematics. = = Essential Question:  How can I use math symbols to describe a pattern? =

**Problem ** ====**Suppose you buy a $195 CD-ROM drive from the Unlimited Store on an installment plan. How many months will it take you to pay for the drive? Describe how you found your answer. **====

The answer is 11 months. I used the symbolic method to complete the problem. Then I double-checked my work using a graphing calculator by putting in the equation y=30+15x and then going in to table mode and then scrolling down until I found $195. Here is my work for how I solved this problem:

y=30+15x 195=30+15x 195-30=165 165 ÷15= 11 x= 11, so 11 months to pay for the $195 CD-ROM drive.

<span style="color: #861da5; font-family: 'Comic Sans MS',cursive; font-size: 27px;">**Follow Up** <span style="font-family: 'Comic Sans MS',cursive; font-size: 16px;">**1.** <span style="font-family: 'Comic Sans MS',cursive;">The sequence in which I solved this problems was that first I substituted y with $195. Then I subtracted $30 from $195 to see how much I would have to actually pay for in my monthly installments. I don't pay for the $195 in monthly installments because I pay $30 upfront and then there is only $165 left that I need to pay for per month. After that I divided the $165 (Amount I need to pay) by $15 (Amount I will pay per month) and I got 11. That means that it will take me 11 months to pay off all the money I need to buy a CD-ROM Drive.

<span style="font-family: 'Comic Sans MS',cursive; font-size: 16px;">**2.** <span style="font-family: 'Comic Sans MS',cursive;">Suppose you buy a fridge from the Unlimited Store for $305 on an installment plan. You pay $35 upfront and then you pay $15 each month. How long will it take for you to pay off all the installments? How many months?

<span style="font-family: 'Comic Sans MS',cursive;">y=35+15x <span style="font-family: 'Comic Sans MS',cursive;">305=35+15x <span style="font-family: 'Comic Sans MS',cursive;">305-35=270 <span style="font-family: 'Comic Sans MS',cursive;">270 ÷<span style="font-family: 'Comic Sans MS',cursive;">15= 18

<span style="font-family: 'Comic Sans MS',cursive;">x= 18, so it will take 18 months to pay for the fridge.

<span style="color: #3bab9c; font-family: 'Comic Sans MS',cursive; font-size: 27px;">**Extra Links** <span style="display: block; font-family: 'Comic Sans MS',cursive; text-align: left;">[|Symbolic Method- Youtube Video] <span style="display: block; font-family: 'Comic Sans MS',cursive; text-align: left;">[|Step-by-Step (TutorVista)]  <span style="font-family: 'Comic Sans MS',cursive;">[|Purple Math, PEMDAS]  <span style="font-family: 'Comic Sans MS',cursive;">[|PEMDAS, YourTeacher Video]  <span style="font-family: 'Comic Sans MS',cursive;">[|Math is Fun :) - PEMDAS]