Six balls are drawn successively from an urn containing $7$ red and $9$ black balls. Determine whether or not the trials of drawing balls are Bernoulli trials when the ball drawn is not replaced in the urn after each draw.

(N/A) For trials to be Bernoulli trials,they must satisfy two conditions: $(i)$ The trials must be independent,and (ii) The probability of success must remain constant for each trial.
In this experiment,the balls are drawn without replacement.
Let $S$ be the event of drawing a red ball (success).
In the $1^{st}$ trial,the probability of success is $P(S_1) = \frac{7}{16}$.
In the $2^{nd}$ trial,if the first ball was red,the probability of success becomes $P(S_2|S_1) = \frac{6}{15}$. If the first ball was black,the probability becomes $P(S_2|S_1^c) = \frac{7}{15}$.
Since the probability of success changes depending on the outcome of the previous trials,the trials are not independent and the probability of success is not constant.
Therefore,the trials are not Bernoulli trials.