Question

Hailey ran a few laps.
\[D(n)\] models the duration (in seconds) of the time it took for Hailey to run her
\[n^{th}\] lap.
\[n\]
\[3\]
\[7\]
\[9\]
\[D(n)\]
\[85\]
\[99\]
\[110\]
When did the lap duration increase faster?
Choose 1 answer:
A
Between the
\[3^\text{rd}\] lap and the
\[7^\text{th}\] lap
B
Between the
\[7^\text{th}\] lap and the
\[9^\text{th}\] lap
C
The lap duration increased at the same rate over both intervals

Answer 1

Compute the average increase per lap on each interval.

From n = 3 to 7: change = 99 − 85 = 14 seconds over 4 laps → 14/4 = 3.5 s per lap.
From n = 7 to 9: change = 110 − 99 = 11 seconds over 2 laps → 11/2 = 5.5 s per lap.

5.5 > 3.5, so B.