STDEV COUNTIF The margin of error in an interval estimate of the population mean is a function of all of the following EXCEPT _.ĭ. Which Excel function would NOT be appropriate to use to construct a confidence interval estimate?ĭ. The population standard deviation is known. A random sample of 200 current owners is selected. 11 117 An auto manufacturer wants to estimate the annual income of owners of a particular model of automobile. 95 probability when the population standard deviation equals 11 is _.ĭ. TERMS IN THIS SET (105) To estimate a population mean, the sample size needed to provide a margin of error of 2 or less with a.
To qualify, a person's z-score must be at least 2.5. This turns out to be 0.0062, which is less than 1%. Find the area above z= 2.5 by subtracting the table entry (0.9938) from 1. What is the minimum IQ that qualifies a person for membership in Mensa? z= 2.50, look at the table which is 0.9938. One typical IQ scale has a mean of 100 and standard deviation 15. Mensa is a society for "geniuses." One way to qualify for membership is having an IQ at least 2.5 standard deviations above average. These typically have right-skewed distributions there are usually a few very expensive homes in any community. there are usually a few expensive homes that are far away from the rest of the data If you really want units for these, they are "standard deviations." The price of homes in a typical community will not have a Normal distribution because _.
When we divide, units cancel, so z-scores have no units. 4) It is measured in the same units as the variable. Which one of the following is a false statement about a standardized value (z-score)?ġ) It represents how many standard deviations an observation lies from the mean.Ģ) All of these statements are true about a standardized value (z-score).ģ) It represents in which direction an observation lies from the mean.Ĥ) It is measured in the same units as the variable. densityĭensity curves are usually thought of as "idealized" or smoothed histograms. TERMS IN THIS SET (21) A _curve is a smoothed histogram. Which is the indicated IQ score +13 more terms 0000 #'s to find the one when rounded to only 2 decimals places =.97Ģ.Convert a standard normal random variable z to a normal random variable x by using the formula below, where μ is the mean and σ is the standard deviation. If a desired value is midway between two table values, select the larger table value. If the exact area is not in the body of the table, avoid interpolation by selecting the closest value. Use the standard normal distribution table to find the z score that has a cumulative area from the left of 0.97. The graph to the right depicts IQ scores of adults, and those scores are normally distributed with a mean of 100 and a standard deviation of 15. Subtract highest z score from 2nd z score 6.3.9įind the indicated IQ score. 7486 = area of shaded region (for when graph has 2 numbers)ĭo everything for both numbers To find the area under a curve that is between the 2 z=#'s 6 in the standard normal distribution table - look acroos columns until you # below. The shaded region in the graph to the right is the area to the left of 0.67 in a standard normal distribution with a mean of 0 and a standard deviation of 1. (graph has 110 indicated as shaded area( x=110 (for when graph only has 1 number)įind the area of the shaded region. Standardizing the scores to z scores makes the distribution a standard normal distribution. What are the value of the mean and standard deviation after all IQ scores have been standardized by converting them to z scores using z=(x-μ)/σ ? The mean is 0 and the standard deviation is 1. TERMS IN THIS SET (17) The distribution of IQ scores is a nonstandard normal distribution with a mean of 100 and a standard deviation of 15.
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