Grade 8 Algebra: Word Problems: Functions

Name: ______________________Date: ____________Score: ____ / 8

Level 2

Interpret a function rule

1. Use ${C = 4h + 10}$ :
$C\text{}$ $\text{is}$ $\text{the}$ $\text{cost}$ $\text{in}$ $\text{dollars}$ $\text{to}$ $\text{rent}$ $\text{a}$ $\text{bike}$ $\text{for}$ $h\text{}$ $\text{hours.}$ $\text{What}$ $\text{do}$ $\text{the}$ $\text{4}$ $\text{and}$ $\text{the}$ $\text{10}$ $\text{mean?}$
2. Use ${T = 2m + 15}$ :
$T\text{}$ $\text{is}$ $\text{the}$ $\text{water}$ $\text{temperature}$ $\text{in}$ $\text{degrees}$ $\text{after}$ $m\text{}$ $\text{minutes}$ $\text{of}$ $\text{heating.}$ $\text{What}$ $\text{is}$ $\text{it}$ $\text{after}$ $\text{10}$ $\text{minutes?}$
3. Use ${d = 60t}$ :
$d\text{}$ $\text{is}$ $\text{the}$ $\text{distance}$ $\text{in}$ $\text{miles}$ $\text{a}$ $\text{train}$ $\text{goes}$ $\text{in}$ $t\text{}$ $\text{hours.}$ $\text{How}$ $\text{long}$ $\text{does}$ $\text{it}$ $\text{take}$ $\text{to}$ $\text{go}$ $\text{210}$ $\text{miles?}$
4. Use ${B = 500 - 25w}$ :
$B\text{}$ $\text{is}$ $\text{the}$ $\text{money}$ $\text{left}$ $\text{in}$ $\text{dollars}$ $\text{after}$ $w\text{}$ $\text{weeks.}$ $\text{After}$ $\text{how}$ $\text{many}$ $\text{weeks}$ $\text{is}$ $\text{the}$ $\text{money}$ $\text{gone?}$
5. Use ${P = 15n - 60}$ :
$P\text{}$ $\text{is}$ $\text{the}$ $\text{profit}$ $\text{in}$ $\text{dollars}$ $\text{from}$ $\text{selling}$ $n\text{}$ $\text{shirts.}$ $\text{How}$ $\text{many}$ $\text{shirts}$ $\text{must}$ $\text{be}$ $\text{sold}$ $\text{to}$ $\text{break}$ $\text{even?}$
6. Use ${H = 3w + 5}$ :
$H\text{}$ $\text{is}$ $\text{a}$ $\text{plant's}$ $\text{height}$ $\text{in}$ $\text{cm}$ $\text{after}$ $w\text{}$ $\text{weeks.}$ $\text{When}$ $\text{is}$ $\text{it}$ $\text{29}$ $\text{cm}$ $\text{tall?}$
7. Use ${C = 0.5m + 20}$ :
$C\text{}$ $\text{is}$ $\text{the}$ $\text{monthly}$ $\text{phone}$ $\text{cost}$ $\text{in}$ $\text{dollars}$ $\text{for}$ $m\text{}$ $\text{minutes.}$ $\text{What}$ $\text{is}$ $\text{the}$ $\text{cost}$ $\text{for}$ $\text{100}$ $\text{minutes?}$
8. Use ${V = 1200 - 150y}$ :
$V\text{}$ $\text{is}$ $\text{a}$ $\text{laptop's}$ $\text{value}$ $\text{in}$ $\text{dollars}$ $\text{after}$ $y\text{}$ $\text{years.}$ $\text{What}$ $\text{is}$ $\text{it}$ $\text{worth}$ $\text{after}$ $\text{4}$ $\text{years?}$