Question

A die is thrown twice what is the probability that 5 will come up either time and 5 will come up at least once

Answer 1

So here is the answer

Answer 2

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The total number of outcome = 6 × 6 = 36

Method 1:

Consider the following events.

A = 5 comes in the first throw,

B = 5 comes in second throw

P(A) = 6/36,

P(B) = 6/36 and

P(not B) = 5/6

So, P(notA) = 1 – 6/36 = 5/6

∴ The required probability = 5/6 × 5/6 = 25/36

Method 2:

Let E be the event in which 5 does not come up either time.

So, the favourable outcomes are [36 – (5 + 6)] = 25

∴ P(E) = 25/36

• Number of events when 5 comes at least once = 11 (5 + 6)

∴ The required probability = 11/36

Hope It's Helpful.....:)