Average Speed lies in between the two speeds. It may not be in the center since the time taken at the two speeds might be different but it does lie somewhere in between them. You cannot drive at two speeds: 50 mph and 60 mph and still expect to average 70 mph. Your average will lie somewhere between 50 and 60.
Similarly, if the average speed is 2.8 and the two speeds are
consecutive integers (otherwise 2 and 3 is wrong), the speeds must be 2 and 3. You cannot have the speeds as (1 and 2) or (3 and 4) since they cannot average out to be 2.8.
Let’s go very slowly.
You did this:
2.8 is between 2 and 3
So you used weighted average:
2 and 3
Since 2.8 is closer to 3,
you got:
2:3 = 1:4
This part is CORRECT.
But what does this 1:4 represent?
It represents how long he spent at each speed.
Why?
Because average speed is naturally weighted by TIME.
Example:
If you drive:
1 hour at 2 mph
4 hours at 3 mph
then average speed is:
(2×1 + 3×4)/(1+4)
= 14/5
= 2.8
So your 1:4 means:
time at 2 mph = 1 part
time at 3 mph = 4 parts
NOT distance.
---
Now convert to distance.
Use:
distance = speed × time
Sunny:
2 × 1 = 2
Cloudy:
3 × 4 = 12
So distances are:
2:12
= 1:6
Total distance parts:
1 + 6 = 7
Sunny fraction:
1/7