Question

A die is tossed thrice. If event of getting an even number is a success. Then the probability of getting at least two successes is A. 7/8 B. 1/4 C. 2/3 D. 1/2 Select the correct answer from above options

Answer 1

Correct Answer - D Let X denote the number of successes in 3 trials. Then, X is a binomial variate with n=3,p= 3 6 = 1 2 such that P(X=r)=.3Cr( 1 2 )3,r=0,1,2,3 ∴ Required Probability =P(X≥2)=P(X=2)+P(X=3) =.3C2( 1 2 )3+.3C3( 1 2 )3= 1 2