8 kilometers is the answer
Hope this helps!:)
One solution let's find that




There's nothing preventing us from computing one integral at a time:



Expand the integrand completely:

Then

Answer:
616/2500
Step-by-step explanation: You first have to find the number of times a Blue marbles was chosen: 22
Then find the total number of marbles that were chosen. Make a fraction out of it: 22/50
You then see how many times tails was flipped: 28
Do the same thing again: 28/50
Then multiply the two fractions together:
22/50 * 28/50 = 616/2500