A spinner is divided into six equal-sized sectors labeled 1 through 6. Dwayne spins this spinner 12 times. Let [tex]$X$[/tex] represent the number of 1s that are spun. What are the mean and standard deviation of [tex][tex]$X$[/tex][/tex]?

A. [tex]\mu_x = 1, \sigma_x = 1.29[/tex]
B. [tex]\mu_x = 2, \sigma_x = 1.29[/tex]
C. [tex]\mu_x = 2, \sigma_x = 1.67[/tex]
D. [tex]\mu_x = 10, \sigma_x = 2.78[/tex]



Answer :

Sure, let's solve this step-by-step.

We will use the properties of a binomial distribution to solve this problem. A binomial distribution is applicable here because:

1. We have a fixed number of trials (12 spins).
2. Each trial has two possible outcomes (either spinning a 1 or not).
3. The probability of success (spinning a 1) is constant on each trial.
4. The trials are independent of each other.

Step 1: Define the random variable

Let [tex]$X$[/tex] represent the number of times the spinner lands on 1. We are dealing with a binomial random variable because of the reasons stated above.

Step 2: Determine the parameters of the binomial distribution

The binomial distribution is characterized by two parameters [tex]\( n \)[/tex] and [tex]\( p \)[/tex]:
- [tex]\( n \)[/tex] is the number of trials, which is 12 (the number of times the spinner is spun).
- [tex]\( p \)[/tex] is the probability of success on each trial. Since the spinner is divided into six equal sectors, the probability of landing on any specific number (including 1) is [tex]\( \frac{1}{6} \)[/tex].

Step 3: Calculate the mean

The mean ([tex]\(\mu\)[/tex]) of a binomial distribution is given by the formula:
[tex]\[ \mu = n \cdot p \][/tex]

Substituting the values of [tex]\(n\)[/tex] and [tex]\(p\)[/tex]:
[tex]\[ \mu = 12 \cdot \frac{1}{6} = 2 \][/tex]

Step 4: Calculate the standard deviation

The standard deviation ([tex]\(\sigma\)[/tex]) of a binomial distribution is given by the formula:
[tex]\[ \sigma = \sqrt{n \cdot p \cdot (1 - p)} \][/tex]

Substituting the values of [tex]\(n\)[/tex] and [tex]\(p\)[/tex]:
[tex]\[ \sigma = \sqrt{12 \cdot \frac{1}{6} \cdot \left(1 - \frac{1}{6}\right)} \][/tex]
[tex]\[ \sigma = \sqrt{12 \cdot \frac{1}{6} \cdot \frac{5}{6}} \][/tex]
[tex]\[ \sigma = \sqrt{2 \cdot \frac{5}{6}} \][/tex]
[tex]\[ \sigma = \sqrt{\frac{10}{6}} \][/tex]
[tex]\[ \sigma = \sqrt{\frac{5}{3}} \approx 1.29 \][/tex]

Conclusion:
The mean ([tex]\(\mu_x\)[/tex]) of [tex]\(X\)[/tex] is 2, and the standard deviation ([tex]\(\sigma_x\)[/tex]) of [tex]\(X\)[/tex] is approximately 1.29.

Therefore, the answer is:
[tex]\[ \boxed{\mu_x=2, \sigma_x=1.29} \][/tex]