Question

If in 6 trials, X is a binomial variate which follows the relation 9P(X = 4) = P(X = 2), then the probability of success is …

(a) 0.125 

(b) 0.25 

(c) 0.375 

(d) 0.75

Answer 1

(b) 0.25

9p² = q² [∵ 6C₄ = 6C₂] 

9p² = (1 – p)²

9p² = 1 – 2p + p² 

8p² + 2p – 1 = 0 

(4p – 1)(2p + 1) = 0