Question

A room cannot exceed the temperature of -20 degrees Fahrenheit, right now it is -72 degrees Fahrenheit. The temperature then starts to rise 6.3 degrees every hour. How many hours are there until the room temperature is surpassed?​

Answer 1

We have 8.25 hours until the room temperature is surpassed.

Explanation:

The initial temperature of the room is -72 F, and it rises 6.3 F every hour, which means after nth hour, the room temperature
`T` will be:

`T = -72+6.4 n`.

Therefore, the room temperature is surpassed when

`-72+6.3n> -20`

we solve for
`n:`

`6.3n> -20+72`

`6.3n> 52`

`\boxed{n> 8.25\:hr}`

Thus, we have 8.25 hours until the room temperature is surpassed.