Expoential Growth: One hundred dollars is invested in 90 day

[orange1998]

One hundred dollars is invested in 90 days. At the end of the term, the investment is worth $120. Find the growth rate per day.

I do NOT get this...
My equation was; 120=100 times b^90. Using the formula y= a times b^x Is that equation right, and how do I solve it? Even if it's not right, just PLEASE help me solve it. Thanks!


Oh, and if/when you do solve this, EXPLAIN? Thanks, cause, I've got 5 more just like this one to solve.

[maggiemagnet]

One hundred dollars is invested in 90 days. At the end of the term, the investment is worth $120. Find the growth rate per day.

I do NOT get this...
My equation was; 120=100 times b^90.

What is the value of b? Where is the "rate" in your equation?

Oh, and if/when you do solve this, EXPLAIN?

There's an explanation of exponential growth here.

[orange1998]

Yeahh, the value of "b" is the rate change, that's what I'm having trouble figuring out. That's what we are looking for.. Thanks for the link.

[orange1998]

The thing is is that they're teaching me stuff with all those different equations, my teacher taught us y=a*b^x and says we should be able to use that to figure out this problem. I'm SUPER confused. Lol

[maggiemagnet]

Okay, if you're supposed to use that equation, then solve for the value of "b". Then interpret this value according to whatever formula they gave you.

[orange1998]

Thanks, I figured it out.