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# Tell me? Minimum number of times a fair coin must be tossed so thatthe probability of getting at least one head is more than 99% is :

Minimum number of times a fair coin must be tossed so that

the probability of getting at least one head is more than 99% is :

• Option 1)

5

• Option 2)

6

• Option 3)

8

• Option 4)

7

Answers (1)
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$P(H)=\frac{1}{2}$

So, probability to get atleast one head = $1-P(no\: \: head)\geq 99$

$\therefore$  $1-\frac{1}{2^{n}}\geq \frac{99}{100}$

$=>\frac{1}{2^{n}}\leq \frac{1}{100}$

$=>{2^{n}}\geq {100}$

$=>n\geq 7$

$\therefore$ Minimum value of n will be = 7

So, option (4) is correct.

Option 1)

5

Option 2)

6

Option 3)

8

Option 4)

7

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