Assertion (A): A binomial distribution with mean 4 and variance 2 has $n = 8$.

Reason (R): The ratio of the variance to the mean is $q$.

Explanation

1. 01

   R: $\frac{npq}{np} = q$. True.

2. 02

   By R, $q = \frac{2}{4} = \frac{1}{2}$, so $p = \frac{1}{2}$ and $n = \frac{4}{1/2} = 8$: A is true and follows from R.