a) the random variable is:
x = the number of aces observed when you draw three random cards.
b) This experiment follows the binomial distribution because when you draw a card with replacement there are two options: it is an ace, or it is not an ace.
The binomial distribution has the next formula:
where:
P(x) = binomial probability
x = number of times for a specific outcome within n trials
nCx = number of combinations
p = probability of success on a single trial
q = probability of failure on a single trial
n = number of trials
In this case, the possible values of x are 0, 1, 2, and 3. The number of trials, n, is 3. The probability of success, p, that is, the probability of drawing an ace from a 52 cards deck is:
The probability of failure, q, that is not drawing an ace is:
Therefore, the probability of drawing zero aces, that is, x = 0, is:
Therefore, the probability of drawing one ace, that is, x = 1, is:
Therefore, the probability of drawing two aces, that is, x = 2, is:
Therefore, the probability of drawing three aces, that is, x = 3, is:
And the table is:
x | P(x)
0 | 0.7865
1 | 0.1966
2 | 0.0164
3 | 0.0004
c) The probability distribution of x is right-skewed (the probability is greater for the smaller values of x)
d) The mean in binomial distribution is calculated as follows: