Salaries for teachers in a particular state have a mean of $ 45000 and a standard deviation of $ 6700.
a. If we randomly select 16 teachers from that district, can you determine the sampling distribution of the sample mean?
- Yes No
- If yes, what is the name of the distribution?
- The mean? This is not a decimal or integer value.
- The standard error?
b. If we randomly select 74 teachers from that district, can you determine the sampling distribution of the sample mean?
- Yes No
- If yes, what is the name of the distribution?
- The mean?
- The standard error?
c. For which sample size would I need to know that population distribution of X, teacher salaries, is normal in order to answer?
d. Assuming a sample size of 74, what is the probability that the sampling error is within $1000. (In other words, the sample mean is within $1000 of the true mean.)
e. Assuming a sample size of 74, what is the 90th percentile for the AVERAGE teacher’s salary?
f. Assuming that teacher’s salaries are normally distributed, what is the 90th percentile for an INDIVIDUAL teacher’s salary?
Definition Definition Measure of central tendency that is the average of a given data set. The mean value is evaluated as the quotient of the sum of all observations by the sample size. The mean, in contrast to a median, is affected by extreme values. Very large or very small values can distract the mean from the center of the data. Arithmetic mean: The most common type of mean is the arithmetic mean. It is evaluated using the formula: μ = 1 N ∑ i = 1 N x i Other types of means are the geometric mean, logarithmic mean, and harmonic mean. Geometric mean: The nth root of the product of n observations from a data set is defined as the geometric mean of the set: G = x 1 x 2 ... x n n Logarithmic mean: The difference of the natural logarithms of the two numbers, divided by the difference between the numbers is the logarithmic mean of the two numbers. The logarithmic mean is used particularly in heat transfer and mass transfer. ln x 2 − ln x 1 x 2 − x 1 Harmonic mean: The inverse of the arithmetic mean of the inverses of all the numbers in a data set is the harmonic mean of the data. 1 1 x 1 + 1 x 2 + ...
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