Question

Assuming that Switzerland's population is growing exponentially at a continuous rate of 0.21 percent a year and that the 1988 population was 6.8 million, write an expression for the population as a function of time in years. (Let t=0t=0 in 1988.)

I got 6.8 e^[0.021(t - 1988)] but it says it's wrong. I don't know what I'm doing wrong.

Answer 1

It is wrong. Your equation uses a rate of 2.1%. a .21% growth rate means

6.8 * 1.0021^(t-1988)

You can use a base of e, but that would be

ln 1.21 = 0.0021

6.8 e^(0.0021(t-1988))

or, if t is defined as the number of years since 1988,

6.8*1.0021^t
or
6.8 e^(0.0021t)

Answer 2

That answer is wrong.