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Matleena chooses three numbers at random from the numbers 1, 2, 3,  10. What is the probability that they are not all consecutive? (For example, the three numbers 6, 7, 8 are consecutive.)

 May 28, 2019
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The consecutive  ones are

1 2 3

2 3 4

3 4 5

4 5 6

5 6 7

6 7 8

7 8 9

8 9 10

 

 

The number of possible combos = C(10,3)  = 120

 

So the probability that they are not consecutive  =  1 = P(that they are consecutive) =

 

1 -8/120  =

 

1 - 1/15  =

 

14 / 15

 

 

cool cool cool 

 May 28, 2019

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