IQ is known to be normally distributed with a mean of 100 and standard deviation of 16. A small school of 64 students has a mean IQ of
105. What is the approximate value of the test statistic associated with this sample mean and what conclusion should be drawn in relation to the overall population?
z = +2.5; reject H0 and conclude that this sample is significantly higher in IQ than the general population
t = -0.27; retain H0 and conclude that the IQ for this sample is not significantly different from the general IQ population
z = +2.0; retain H0 and conclude that the IQ for this sample is not significantly different from the general IQ population
z = +2.5; retain H0 and conclude that the IQ for this sample is not significantly different from the general IQ population
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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