Query about Question 1 from "PrepSwift: Words to Algebra II" [3327]

https://prepswift.gregmat.com/quizzes/quiz/prepswift-words-to-algebra-ii (Question 1)


If we are calculating the average speed, why don’t we need to divide the two weighted speeds by 2 to get the average? Aren’t you just calculating the total distance? And why does “k” disappear?

Is it supposed to do anything?

I don’t know why it says question 1 here, but I am referring to question 5.

I guess we don’t need k because we can just look as k being the total duration and then 0.8 of the duration was done in a certain speed and 0.2 in another speed.

But what about the calculation itself? Why don’t you divide the two weighted speeds by 2 to get the average? What the solution is calculating is time*speed with is distance, not average speed.

I’m not following you - can you sketch your full solution?