, 2023

Lonnie rests for 30 s between the 1st and 2nd sprints, the 2nd
and 3rd sprints, and so on up to and including the 23rd and 24th
sprints.

Thus, Lonnie takes the 30 s rest 23 times.
Since Lonnie sprints at a constant speed of 8 m/s, then it takes
Lonnie $\text{200}$ m}}{8 $\text{}$
m/s}}=25$ s to sprint 200 m.

Lonnie completes 24 such sprints, and so his time spent sprinting is
$24\times25\text{ s}=600$ s.

Lonnie also takes 23 rests, each of length 30 s, and so his time spent
resting is $\$23\times30\text{ s}=690\text{}$
s}$.

On Monday, Lonnie’s total practice time is thus $600 \text{ s}+690 \text{ s}=1290$
s.
Solution 1

On Tuesday, each of Lonnie’s 240 m sprints takes $\dfrac{240 \text{ m}}{8 \text{ m/s}}=30$
s, and so Lonnie spends $\$20\times 30\text{ s}=600\text{}$ s}$ sprinting.

Lonnie rests 19 times, and so he rests for a total of $19\times 30\text{ s}=570\text{ s}$.

On Tuesday, Lonnie’s total practice time is thus $600 \text{ s}+570 \text{ s}=1170$ s, and
so Tuesday’s practice takes $1290-1170=120$ fewer seconds compared to
Monday’s practice.

Solution 2

On Monday, Lonnie sprints $24 $\times 200 \text{}$ m}=4800$ m.

On Tuesday, Lonnie also sprints $20 $\times 240 \text{}$ m}=4800$ m.

Since Lonnie sprints at the same constant speed on both days, then he
spends the same amount of time sprinting on each of the two days.

Thus, the difference between the length of time that Lonnie practices on
the two days is the difference between the time that he spends resting
between sprints.

Lonnie rests 23 times on Monday, and he rests 19 times on Tuesday.

Since he rests 4 more times on Monday than he does on Tuesday, then
Tuesday’s practice takes $\$4\times$
30=120$ fewer seconds compared to Monday’s practice.