(b) Mean$= np = 4$, variance$= nqp = 3$ On solving, we get $q = \frac{3}{4},\ n = 16,p = \frac{1}{4}$ Now, $P(X \geq 1) = 1 - P(X = 0) = 1 -^{n}C_{0}p^{0}q^{n - 0}$ $= 1 - \left( \frac{3}{4} \right)^{16}$
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