A number is chosen at random from 1 to 100…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A number is chosen at random from to . Find the probability that it is not a multiple of , as a decimal.
Need a reminder? The key ideaShow
The complement of is . Every outcome favours exactly one of them, so and . When an event is hard to count, count its complement.
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 multiples. : numbers.
Step 2. The event. .
Step 3. The complement. .
Answer: .
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