Question

Starting from 105 feet away, a person on a bicycle rides towards a checkpoint and then passes it. The rider is traveling at a constant rate of 35 feet per second. The distance between the bicycle and the checkpoint is given by the equation d=|105-35t|. At what times is the bike 60 feet away from the checkpoint?
A. 1.3 sec and 2.6 sec
B. 1.3 sec and 4.7 sec
C. 1.1 sec and 2.6 sec
D. 4.7 sec and 9.4 sec

Answer 1

The given distance formula is:

d = | 105 – 35 t|

 

There are two working equations here due to the absolute symbol.

a. d = 105 – 35 t

b. d = 35 t – 105

 

From a:

60 = 105 – 35 t

t = 1.3 seconds

 

From b:

60 = 35 t – 105

t = 4.7 seconds

 

So the answer is:

B. 1.3 sec and 4.7 sec