making linear equation from word problem

At low altitudes, the altitude of a parachute and time in the air are linearly related. A jump at 2,880 ft use the US army T-10 parachute system last 120 sec.

(A) find a linear model relating altitude a (in feet) and time in the air t (in seconds)

(B) the rate of descent is the speed at which the jumper falls. What is the rate of descent for a T-10 system?

3 answers

if time at altitude x is y, then
y = ax+b

Now, b=0, since a jump from 0 feet takes 0 time. So,
y = ax
120 = 2880a
a = 120/2880 = 12/288 = 1/24

y = x/24

the speed is thus ft/s = x/y = 24 ft/s

Thank you

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