Question

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:

• A. $5$
• B. $6$
• C. $7$
• D. $8$

Answer 1

The correct option is C $7$

$1-{\left(\frac{1}{2}\right)}^n>\frac{99}{100}\Rightarrow {\left(\frac{1}{2}\right)}^n<\frac{1}{100}\Rightarrow n=7$