Pre-calculus problem help?

An inheritance of $12,000 is invested in two different mutual funds. One fund pays 5 1/2% simple interest and the other pays 8% simple interest.


a. If x dollars is invested in the fund paying 5 1/2%, how much is invested in the fund paying 8%?


b. Write the annual interest y in terms of x.


c. Use a graphing utility to graph the function in part b over the interval 0 is less than or equal to x which is less than or equal to 12,000.


d. Explain why the slope of the line in part c is negative.

Pre-calculus problem help?
A) let y be the amount invested in the 8% fund





B) couple steps involved here...





$12,000 = y + x


y = $12,000 - x


Annual interest y = Principal * Rate * Time


Annual interest y = (y * 8%) * 1 year


Annual interest y = ($12,000 - x) * (0.08) * 1


Annual interest y = ($12,000 - x) * (0.08)


Annual interest y = $960 - 0.08x





C) can't exactly help you here. just graph it yourself and make sure your domain is 0 is less than/equal to x and x is less than/equal to 12,000. you can go to webgraphing.com to help you make a graph.





D) i'm not sure of an answer here but my guess is..the slope is negative because as X gets larger, annual interest Y will get smaller because if X gets bigger, that means the amount of money deposited into the 8% account is smaller thus resulting in less annual interest.