Question

When Nicole left her house in the morning, her cell phone battery was partially charged. The charge remaining in Nicole's battery, as a percentage, can be modeled by the equation B=-9t+72,B=−9t+72, where tt is the number of hours since Nicole left her house. What is the slope of the equation and what is its interpretation in the context of the problem?

Answer 1

The form of the linear equation is

`y=mx+b`

m is the rate of change (slope)

b is the initial amount

Since the equation of the remaining Nicole's battery as a percentage is

`B=-9t+72`

By comparing the 2 forms of the equation above, then

`m=-9`

Since m represents the slope, then

The slope of the function is -9

Since the function represents the remaining amount of charge as a percent, then

The slope means:

The percentage charge that Nicole's phone loses each hour

The answer is:

The slope of the function is -9 which reveals the percentage charge that Nicole's phone loses each hour