Probability Practice Test 1

Question : 11 of 40

Marks: +1, -0

In order to get at least once a head with probability ≥ 0.9, the number of times a coin needs to be tossed is

Solution:

Probability of getting at least one head in n tosses

= 1 - (1/2)^n ≥ 0.9

⇒ (1/2)^n ≤ 0.1

⇒ 2^n ≥ 10 ⇒ n ≥ 3

Hence, least value of n = 4.

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