Question

The formula NEXT = 2 • NOW models the number of bacteria in a test tube. There were 10 bacteria in the test tube after the first hour. How many bacteria will be present in the test tube after the fifth hour?

Answer 1

160

Explanation:

NEXT = 2 • NOW

Implies

a(n+1) = 2 × a(n)

a(1) = 10

a(2) = 20

a(3) = 40

a(4) = 80

a(5) = 160

Answer 2

160 bacteria

Explanation:

We can create an exponential function of the form:
`y=ab^(x-1)`, where a is the initial value, b is the rate, and x is the time.

Here, a = 10 and b = 2, so our equation is:

`y=ab^(x-1)`

`y=10*2^(x-1)`

We want the number of bacteria present after the fifth hour, or when x = 5, so we have:

`y=10*2^(x-1)`

`y=10*2^(5-1)=10*2^(4)=10*16=160`

There were 160 bacteria.