Answer:
Jack ran 704 ft/min during the second half of the race.
Step-by-step explanation:
Here the distance traveled was 3 miles, and the total elapsed time was 20 minutes. Recall that distance = rate * time, or rate = distance / time.
Find the pace (speed, rate) for the second part of the race.
Here, the total distance was 3 miles and the elapsed time 20 minutes. Jack's average speed was thus 3/20 miles/minute. Converting this to feet per minute, we get:
3 mi 5280 ft
------------ * ------------- = 792 ft/min (Jack's average speed)
20 min 1 mi
Recall that the formula for finding the average of x and y is (x + y) / 2.
(1/2)(880 ft/min + p) = 792 ft/min; find p, which represents Jack's pace for the second part of the race.
If (1/2)(880 ft/min + p) = 792 ft/min, and we mult. both sides by 2, we get:
880 ft/min + p = 1584 ft/min.
To solve this for p, subtract 880 ft/min from both sides, obtaining:
p = 704 ft/min
Jack ran 704 ft/min during the second half of the race.
