I need help solving this problem!!

Question

You are going for a walk in the park. For the first 73.75 minutes, you are feeling rather energetic and walk at a rate of 3.93 miles per hour. Suddenly, a ferocious looking butterfly starts chasing you so you run for a couple minutes as fast as you can. Having escaped the vicious butterfly, you continue to walk for an additional 18.89 minutes at a rate of 2.79 miles per hour. The whole walk took 97.81 minutes, and your fitness tracker says you travelled 7.63 miles. What was your average rate of speed over the entire walk? Report your answer in miles per hour, "mph".

Answer 1

distance divided by time = speed

d/t = s

97.81 minutes = 97.81/60 hours = about 1.63 hours total time

d/t

=total distance divided by total time

=7.63/(97.81/60)

= about 4.68 mph

which is probably the answer you want

(yet it doesn't use the additional information in the problem, breaking down the time into walk and run times)

SO maybe , "whole walk"isn't referring to the entire distance, just the "walk parts" and "whole walk" is different from "entire walk" which includes the "run part"?

then 97.81-18.89-73.75= 97.81-92.64= 5.17 minutes running

73.75/60 hrs. at 3.93 mph

5.17/60 hr. at run speed

18.89/60 hr. at 2.79 mph

find the run distance, then

find run speed and then find the weighted average speed

total distance 7.63 miles

d=st

1st walk distance = 3.93(73.75/60) = about 4.83 miles

2nd walk distance = 2.79(18.89/60) = about 0.88 miles

4.83+0.88= 5.71 miles so, the run part = 7.63-5.71 =1.92 miles

run distance = 7.63 - 3.93(73.75/60) - 2.79(18.89/60) = 1.92 miles

then run speed = d/t = 1.92/(5.17/60) = about 22.3 mph

use a weighted average of 3.93, 2.79, and 22.3 mph

Go with 4.68 mph as it is greater than 3.93 and 2.79, reflecting a faster positive run speed in between

take a weighted average of speeds, weighted by time at each speed

22.3(5.7) + 3.93(73.75) + 2.79(18.89)

= 457.8231

divide by total time 97.81

457.8231/97.81

= 4.68 mph = average speed

same as just dividing total distance by total time = 7.63/(97.81/60) = 4.68 mph