24.(i) A die is thrown twice. What is the probability that  5 will not come up either time?

Answers (1)
H Harsh Kankaria

When a die is thrown twice, the possible outcomes =

\{(x,y): x,y\in\{1,2,3,4,5,6\}\}

Total number of possible outcomes = 6\times6 = 36

The outcomes when 5 comes up either on them =

{(5,1), (5,2), (5,3), (5,4), (5,5), (5,6), (1,5), (2,5), (3,5), (4,5), (6,5)}

Number of such favourable outcomes = 11 

\therefore P(5\ will\ come\ up\ either\ time) = \frac{11}{36}

\therefore P(5\ will\ not\ come\ up\ either\ time) = 1-\frac{11}{36} =\frac{25}{36}

Therefore, the probability that 5 will not come either time is \frac{25}{36}

 

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