Answer:
D) 5 feet per second
Explanations:
Let the amount of time to finsh the race be represented by t
Let the average speed be represented by s
Tha amount of time is inversely proportional to the average speed. This can be represented mathematically as:
t α 1/s
Introducing a constant of proportionality, k
t = k/s.............................(*)
A swimmer finishes a race in 200 seconds with an average speed of 3 feet per second
t = 200 seconds
s = 3 feet per second
Substitute t = 200 and s = 3 into equation (*)
200 = k / 3
k = 200(3)
k = 600
To find the average speed of a swimmer that uses 120 seconds to finish the race
t = 120
To get the value of s, substitute k = 600 and t = 120 into the equation (*)
t = k/s
120 = 600/s
120s = 600
s = 600/120
s = 5
The average speed of the swimmer that uses 120 seconds to finish the race is 5 feet per second