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A spinner contains the numbers 1 through 40. What is the probability that the spinner will land on a number that is not a multiple of 9? Give your answer as a fraction.

User Ido Naveh
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1 Answer

13 votes
13 votes

To solve this question, let us first list out the multiples of 9 between 1 and 40

The multiples of 9 are 9, 18, 27, 36.

To get the probability that the spinner lands on a number that is not a multiple of 9.

We can use the relationship:


1-P(9)

Where P(9) is the probability of obtaining a multiple of 9

Let us get P(9) first. Since there are 4 multiples of 9 between 1 and 40


P(9)=\frac{n\\u\text{mber of multiples }}{total\text{ numbers}}=(4)/(40)=(1)/(10)

Next, we will subtract this value from 1


1-(1)/(10)=(10-1)/(10)=(9)/(10)

The answer is:


(9)/(10)

User Dave Peck
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