25 metres. Because 1/10th of a kilometre is a 100 metres. And four athletes divided by 100 metres is 25 metres.
1 = 32
2 = 148
3 = 32
4 = 148
5 = 32
6 = 148
7 = 32
8 = 148
5 Girls + 3 Boys =8 (sample size)
Probability of choosing 1 boy P(1 B) = 3/8
Probability of NOT CHOOSING ANY BOY = 1-3/8 =5/8
Now apply the binomial probability to choose 3 Boys:
8C3(3/8)³(5/8)⁵ ==>P(All boys) = 0.28