The minimum number of times a fair coin needs to be tossed, so that the probability of getting at least two heads is at least 0.96 is :

Explanation

`p=1/2,q=1-1/2=1/2`

`P(r)=nC_r*p^r*q^(n-r)`

r success in n trials

Required probability=1-P(1)-P(0)

`P(1)=nC_1*(1/2)^11*(1/2)^(n-1)`

`P(1)=nC_1*(1/2)^n`

`P(0)=nC_0*(1/2)^0*(1/2)^n`

`=(1/2)^n`

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