A 10. Alice is in a 20-km running race. She
always runs the first half at an average
speed of 2 km/h faster than the second
half.
a) Let x represent her speed in the first
half. Determine a simplified expression
in terms of x for the total time needed
for the race.
b) If Alice runs the first half at 10 km/h,
how long will it take her to run the
race?

After surveying students in her homeroom, katie decided to use a number cube to predict the probability that a randomly chosen student in her school planned to stay after school today for extracurricular activities. in katie’s simulation, a roll of 1 represents staying after school, while rolls of 2, 3, 4, 5, or 6 represent leaving school at the end of classes. according to katie’s model, what is the probability that three randomly chosen students will all stay after school for extracurricular activities today?