# Repaying Loans

As the end of the year approaches rapidly, we’ll now shift our focus toward understanding money and finance. Our first exploration will look at how interest rates and the duration of loans combine to impact the cost of borrowing money.

As you complete your homework, you’ll need to use an online calculator to find the monthly payment for a given set of loan terms. One calculator can be found at Bankrate.com. Alternatively, you can use an Nspire calculator with the function tvmPmt. The required parameters for the function are: number of months, interest rate (leave off the percent), loan amount, 0 (zero), 12, 12. For a loan of $5,000 for 36 months at 15% interest, your function would be entered as tvmPmt(36,15,5000,0,12,12) and would return -173.327. You should get the same result entering those criteria on a web-based calculator. If you want to calculate the old-fashioned way, you can use the following formula. $\text{R=}\frac{\text{P}\cdot \text{i}}{\text{1-(1+i}{{\text{)}}^{\text{-n}}}}$ $\begin{array}{l}\text{R=monthly}\ \text{payment}\\\text{P=loan amount}\\\text{i=monthly interest rate in decimal}\\\text{n=number of payments}\end{array}$ You will have to convert the annual interest rate in percent to decimal and divide by 12 to get the monthly interest rate. Personally, I’d stick with the web calculator, but I thought you might like to see the alternatives. In class we mostly discussed short-term loans. You may have heard the President encouraging people to convert to 15 year mortgages. Compare these two options. Joanne purchases a$150,000 home using a 30 year mortgage at 5.5% interest.

Bob purchases a similar \$150,000 home with a 15 year mortgage at 5.5% interest.

What is the cost of each loan? How much more interest will Joanne pay compared to Bob?

# Upcoming Due Dates

Several important dates are rapidly approaching.

On Thursday, April 2nd, we take the 2nd exam of this 6 weeks covering scatter plots, samples, comparing populations, finding slopes and equations for lines, etc.

On Friday, April 3rd, you must turn in your completed data analysis for the weather project. I will be more than happy to answer questions before or after school. You may also submit questions via e-mail or twitter.

The following week on Thursday, April 9th, you must turn in the written portion of your final project and be ready to present. Not all groups will get to present on Thursday, but you must be ready. Luck of the draw will not save you if your written portion is not complete.

The 7th grade writing STAAR is now behind you, so breathe a great sigh of relief!

# Scatter Plots and Fits — 14.1-14.2

Today’s assignment comes from the green book. We’ve come full circle, as we started with an inquiry lab delving in to scatter plots and association. Today we’ve made it back there, examining linear fits and making predictions based on scatter plots.

Try all the problems assigned. If you don’t know how to do it, try writing down what you know. You’ll be surprised how often that’s all you need to do in order to find the steps to keep going.

14.1—5-7,10,11,13,14
14.2—11-15

# 5.2 Writing Linear Equations from Tables

It’s time for more practice in finding equations for lines! Yesterday, you practiced writing equations from situations. How can you extend that knowledge and skill-set to find linear fits to data in tables? Can you write your equations without graphing first?

How can you apply your recent calculator skills to check your work? If you need help in setting these problems up on the Nspire handhelds, see Mr. Dunn before school or during lunch.

Practice problems for this section (Due at the beginning of class on Wednesday) are:

9, 12, 13, 15

# 5.3 Linear Relationships and Bivariate Data

Try problems 1-6 in guided practice tonight. You may need to refer to chapter 5.3 in your green books.

On Friday, you’ll need to complete 9-13, 15, 17, & 18.

There will be no homework check on Friday. All problems assigned from chapter 5.3 should be completed  and checked before class on Monday. Don’t forget to check odd answers in the back of your book. Be ready with questions when you come to class. You should have many!