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A made-up record shows that a school bus was late on 21 of 75 school days…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A made-up record shows that a school bus was late on of school days. Use the record to estimate the probability that the bus is late on a school day. Then estimate how many late days to expect in a school year of days, and the probability that the bus is on time.
Need a reminder? The key ideaShow
A relative frequency is the number of times an event happened divided by the number of tries. With equally likely outcomes, is the number of outcomes in divided by all outcomes. The probabilities of all the outcomes add up to .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The relative frequency. .
Step 2. The expected count. , so about late days.
Step 3. On time. .
Answer: , about days and .
Check. late days and days on time add up to days.
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