Math CentralQuandaries & Queries


Question from Peter, a student:

What is the probability that if you multiply two randomly selected two digit whole numbers, the result is greater that 100 and less than 200. Express your answer as a common fraction.

Hi Peter,
There is two things you need to consider for the problem:
- How many products of two digit numbers are between 100 and 200? (try a times table like below)
-How many combinations of two digit numbers are there?

I suggest using a times table to determine the number of products between 100 and 200. Don't be intimidated since you will not have to multiply all combinations of two digit numbers. To determine how many combinations of randomly selected pairs of two digit numbers there are consider how many two digit numbers there are and how many of these two digit numbers you are choosing at one time.

For further help check out this review on combinations
and on probability


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