Question

In order to keep a specific bacteria alive, the tempature in a science lab, cannot exceed -20F. The electricity went out, when the tempature was -72F, but is increasing at a rate of 6.5 per hour. How many hours do the scientist have until the bacteria is not safe?

Answer 1

At most 8 hours

Explanation:

Given

`Maximum = -20F`

`Rate = 6.5/hour`

`Base\ Temperature =-72F`

Required

Determine the time taken

Represent time by t.

The relationship between all parameters is:

`Maximum = Base\ Temperature + Rate * t`

`Base\ Temperature + Rate * t \leq Maximum`

This is so (≤) because, according to the question, the temperature can not exceed the maximum.

So, we have:

`-72 + 6.5*t \leq -20`

`-72 + 6.5t \leq -20`

Collect Like Terms

`6.5t \leq -20 + 72`

`6.5t \leq 52`

Solve for t

`t \leq 52/6.5`

`t \leq 8`

Hence, they have at most 8 hours