Question

In order to get at least once a head with probability is greater than or equal to 0.9. the minimum number of times a coin needs to be tossed is

• A. 3
• B. 4
• C. 5
• D. 6

Answer 1

The correct option is B 4

$Given1-{\left(\frac{1}{2}\right)}^n\ge 0.9\Rightarrow 2^n\ge 10\Rightarrow n\ge 4,$, therefore least value of n = 4.