Mark starts a rock climb when he is 1 mile above sea level. He can climb at the rate of 1.5 miles per hour. Which of the following functions would express Mark's height above sea level over time?

f(x) = 1.5x
f(x) = 1 + 1.5x
f(x) = 2.5x

Question

Mark starts a rock climb when he is 1 mile above sea level. He can climb at the rate of 1.5 miles per hour. Which of the following functions would express Mark's height above sea level over time? 



f(x) = 1.5x
f(x) = 1 + 1.5x
f(x) = 2.5x

anonymous · Answer

The correct answer is B. 1.5 is your slope and you start at 1.  Therefore using y=mx+b, where your m=1.5 and b=1. f(x)=1+1.5, you just swapped the form around.  There you go!