Answer:
At most 8 hours
Step-by-step explanation:
Given
[tex]Maximum = -20F[/tex]
[tex]Rate = 6.5/hour[/tex]
[tex]Base\ Temperature =-72F[/tex]
Required
Determine the time taken
Represent time by t.
The relationship between all parameters is:
[tex]Maximum = Base\ Temperature + Rate * t[/tex]
[tex]Base\ Temperature + Rate * t \leq Maximum[/tex]
This is so (≤) because, according to the question, the temperature can not exceed the maximum.
So, we have:
[tex]-72 + 6.5*t \leq -20[/tex]
[tex]-72 + 6.5t \leq -20[/tex]
Collect Like Terms
[tex]6.5t \leq -20 + 72[/tex]
[tex]6.5t \leq 52[/tex]
Solve for t
[tex]t \leq 52/6.5[/tex]
[tex]t \leq 8[/tex]
Hence, they have at most 8 hours