The average teacher's salary in Connecticut (ranked first among states) is $57,337. Suppose that the distribution of salaries is normal with a standard deviation of $7,500. If we sample 100 teachers' salaries, what is the probability that the sample mean is less than $56,000.

Respuesta :

Answer:

The probability that the sample mean is less than $56,000 is 0.0375.

Explanation:

Let X = teacher's salary in Connecticut.

The random variable X follows a Normal distribution with parameters μ = $57,337 and σ = $7,500.

A random sample of n = 100 teacher's salaries are selected.

The sample mean of every sample of 100 salaries will follow a normal distribution with mean μ and standard deviation σ/√n.

Compute the probability that the sample mean of the 100 salaries is less than $56,000 as follows:

[tex]P(\bar X<56000)=P(\frac{\bar X-\mu}{\sigma/\sqrt{n}}<\frac{56000-57337}{7500/\sqrt{100}})\\=P(Z<-1.78)\\=1-P(Z<1.78)\\=1-0.9625\\=0.0375[/tex]

*Use a z-table for the probability.

Thus, the probability that the sample mean is less than $56,000 is 0.0375.

Ver imagen warylucknow

The probability that the sample mean is less than $56,000 is 0.0375.

Calculation of the probability:

Since average teacher's salary is $57,337. The standard deviation of $7,500. So,

Here,

= 7500/sqrt(100) = 750

Now

= Pr[x-bar < 56000]

= Pr[z < ((56000-57337)/750)]

= Pr[z < -1.78]

= 0.0375

hence, The probability that the sample mean is less than $56,000 is 0.0375.

Learn more about probability here: https://brainly.com/question/24601965