Question

The number of bacteria in a petri dish doubles

each hour. There were initially 300 bacteria in the
dish. When the scientist checked again there were
4,800 bacteria. How much time passed?
​

Answer 1

4 hours

Explanation:

The exponential growth equation is given by

y = a (b)^(x)

where a is the initial value, b is the growth rate and x is the time from the initial value

We know the initial value is 300 and the growth rate is 2

y = 300 (2)^(x)

We want to know the time when we have 4800 bacteria

4800=300 *2^(x)

Divide each side by 300

4800/300 = 300/300 * 2^(x)

16 = 2^(x)

Rewrite 16 as a power of 2

2^4 = 2^(x)

x=4

It will take 4 hours