Help with exponential function word problem

[linapril]

The number of bacteria in a culture is given by B(t) = 40e^0.6t, where t is the time in days.
How many bacteria are there after 2 days?
I substituted t = 2, and got this:

2B = 40e^1.2
which I simplified to become this
B = 66.4 days

Apparently this answer is wrong though, can someone explain why?

 

[I like Serena]

The number of bacteria in a culture is given by B(t) = 40e^0.6t, where t is the time in days.
How many bacteria are there after 2 days?
I substituted t = 2, and got this:

2B = 40e^1.2
which I simplified to become this
B = 66.4 days

Apparently this answer is wrong though, can someone explain why?

Hi linapril! :)

After substitution you have B(2) = 40e^1.2
The left side B(2) is not a multiplication.
B(2) is a special notation that represents the number of bacteria after 2 days.
We say that B is a function of time.

So your answer is just 40e^1.2 = 132.8 days.

 

[HallsofIvy]

However, the answer is NOT "132.8 days" it is, rather, 132.8 bacteria.