Poli 761 (a fictitious substance) decays by about 7% every day. How much of a 88 pound sample remains after 9 days?
3 answers
I thought it would just be A = 88e^(0.07*9), which equals 165.23 pounds, but apparently that's not correct...
You can't always just plug in e for the base of the exponent. After 1 day, .93 remains. After t days, .93^t remains. So, we have
88 * .93^9 = 45.80 lbs
Now, if you want to use e as the base, recall that .93 = e^ln(.93) = e^-.0725
So, .93^t = e^(-.0725t)
In your formula, you have the amount growing, since e^.07 is greater than 1.
88 * .93^9 = 45.80 lbs
Now, if you want to use e as the base, recall that .93 = e^ln(.93) = e^-.0725
So, .93^t = e^(-.0725t)
In your formula, you have the amount growing, since e^.07 is greater than 1.
ok thanks
1 answer