Find the mean of the binomial random variable. Round to two decimal places when necessary.
-A die is rolled 4 times and the number of times that two shows on the upper face is counted. If this experiment is repeated many times, find the mean for the random variable X, the number of twos.
A)3.33
B)0.67
C)1.33
D)1

Question

Find the mean of the binomial random variable. Round to two decimal places when necessary.
-A die is rolled 4 times and the number of times that two shows on the upper face is counted. If this experiment is repeated many times, find the mean for the random variable X, the number of twos. 
A)3.33
B)0.67
C)1.33
D)1

Quizplus · Accepted Answer

The mean of a binomial random variable is given by $ \mu = np $, where $ n $ is the number of trials and $ p $ is the probability of success on a single trial. Here, $ n = 4 $ (since the die is rolled 4 times) and $ p = \frac{1}{6} $ (since the probability of rolling a two on a six-sided die is 1 out of 6). Thus, $ \mu = 4 \times \frac{1}{6} = \frac{4}{6} = 0.67 $.

Find the Mean of the Binomial Random Variable