For items 1 through 12, fill in the blank with the correct response (6 points each). 1. We typically assume that variables are distributed because we know how well this shape fits most data distributions. 2. What percent of cases under the normal curve fall within plus or minus one standard deviation of the mean? 3. In a normal distribution, you have a percent chance of randomly selecting a case that falls within plus or minus three standard deviations of the mean. 4. If you run an analysis and find that the mean is 64 and the standard deviation is 7, exactly 68.26 percent of cases will fall between what two values? 5. What percent of cases under the normal curve fall within plus or minus two standard deviations of the mean? 6. If you run an analysis and find that the mean is 79 and the standard deviation is 11, exactly 95.44 percent of cases will fall between what two values? 7. In a normal distribution, you have a percent chance of randomly selecting a case that falls within two standard deviations (above or below) of the mean. 8. What percent of cases under the normal curve fall within plus or minus three standard deviations of the mean? 9. If you run an analysis and find that the mean is 42 and the standard deviation is 2, exactly 99.72 percent of cases will fall between what two values? 10. If we convert raw scores to units of the raw score distribution's standard deviation, we are creating 11. is a deliberate sampling process that makes the laws of probability work. 12. In a normal distribution, you have a percent chance of randomly selecting a case that falls within one standard deviation (above or below) of the mean.
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Assume Z is a standard normal random variable with mean 0 and variance 1. Find the z-score for which the area to its RIGHT is 0.44. Note: Enter X.XX with at least one digit before the decimal and two after, and round up. Thus, 27 is entered as 27.00, 3.5 is entered as 3.50, 0.3750 is entered as 0.38.
Sheryl E.
10.) If a random variable X has a normal distribution with mean 10 and standard deviation 5, the 25th percentile of the distribution of the random variable equals 0.2908 0.4432 0.5587 0.6276 0.7034 11.) If a random variable X has a normal distribution with mean 10 and standard deviation 5, the upper quartile (or the 75th percentile) of the distribution of the random variable equals 10.12 10.56 11.08 12.19 13.37 12.) If a random variable X has a normal distribution with mean 10 and standard deviation 5, the top 1% cutoff of the distribution of the random variable equals 21.63 20.45 20.18 19.88 19.25 13.) If X has a normal distribution with mean 10 and variance 4, Y has a normal distribution with mean 6 and variance 5, and the two random variables are independent, what is the distribution of X + Y? Normal with mean 16 and variance 9 Normal with mean 16 and variance 3 Normal with mean 16 and variance 1 Normal with mean 4 and variance 3 None of these 14.) A random variable X is normal with mean 16 and variance 9. What is the z-score of x = 22? 0.5 1 2 2/3 None of these 15.) If X has a standard normal distribution, then the probability that X is greater than 0.28 equals 0.3512 0.3371 0.3652 0.3710 0.3897 16.) For any normal distribution random variable X, which of the following is wrong? with chance around 68%, X falls within one standard deviation of the mean with chance around 95%, X falls within two standard deviations of the mean with chance around 99.7%, X falls within three standard deviations of the mean All of the above are correct. All of the above are wrong.
Sri K.
1) Choose from the Following: Gaussian Distribution, Empirical Rule, Standard Normal, Random Variable, Inverse Normal, Normal Distribution, Approximation, Standardized, Left Skewed, or Z-Score. Same as the Normal Distribution A statement whose reliability is based upon observation and experimental evidence; formulas based upon experience rather than mathematical conclusions. A [_______ ________] is a quantity resulting from a random experiment that can assume different values by chance. A result that is not exact, but is accurate enough for some specific purposes. The normal distribution that has a mean of zero and standard deviation of one is called the [________ _________]? [____________________] data always have a mean of 0 and a standard deviation of 1 regardless of μ and σ. The [_______] is also referred to as the standard normal deviate or just the normal deviate. Theoretically, the mean, median, and the mode are all equal for any [____________ ____________]. Due to its continuous nature, the normal function can be inverted so that endpoints of intervals may be derived from probabilities. In a [_________________] distribution, we expect that the median will be greater than the mean. 2) The mean amount of gasoline and services charged by Key Refining Company credit customers is $70 per month. The distribution of amounts spent is approximately normal with a standard deviation of $10. What is the probability of selecting a credit card customer at random and finding the customer charged between $70 and $83? (Round to four decimal places).
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