First Order Decomposition -> % of compound. Please help

[lucky_star]

First Order Decomposition -> % of compound. Please help!

Homework Statement

In a first order decomposition, the constant is 0.00313 sec-1. What percentage of the compound has decomposed after 7.17 minutes?

Homework Equations

rate = ln[A]_o - ln[A]_t = kt

The Attempt at a Solution

I feel bad because I have no idea how to solve this problem. My 1st test is soon to come, please help me!

 

[lucky_star]

Oh, please ignore this message because I got the answer already. After talking with my friend for awhile, I finally understand how to work this problem out. I am sorry if I ever bother you.