Hi -

I am a student from Chandler-Gilbert Community College. I am in MAT 151 also known as College Algebra. I am somewhat behind in my work but am hung up on one question. It is a calculator problem. For reference I have a TI-83+. Attached is the relevant document I am working on:

Do not worry about the blank answers, I can solve them on my own. What I am stuck on is how my teacher got her answer (as noted in the top right section if you can read my handwriting) . In this section we are dealing with % Change and Change Factor. I understand those concepts but am having trouble with entering the answer on the calculator.

So the question is:

_{After starting with 78 micrograms, the mass of bacteria decreases by 35% every 2 hours.}

_{a) Determine the amount of time it will take for the mass of bacteria to decrease by 50%}

So the 2 hour CF is 1 - .35 = 0.65. To get the 1-hour Change Factor, I would raise like this: 0.65^1/2 = 0.8062 because a^n/m with 'm' being the denominator of the original Change Factor.

The problem then becomes an algebra problem since it is asking the amount of time it will take a mass of bacteria to decrease by 50%.

0.8062^t = 0.5

t = 3.218

My question is how do I solve for t on the calculator? I am not sure how to get t on the calculator or by hand.

Thanks and hope to hear from you soon.