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4 cards from this section. Quick, good the night before a test.
Calculate the Z-score for X = 80 with mean μ = 75 and σ = 5.
Use the Z-score formula: Z = (X - μ) / σ.
If the mean is 100 and σ is 10, what is Z for X = 90?
Subtract the mean from the value, then divide by the standard deviation.
What is the mean of a standard normal distribution?
Remember the defining properties of the standard normal distribution.
True or False: A Z-score of -1 indicates a value below the mean.
Visualize the normal distribution; below the mean corresponds to negative Z-scores.
A factory produces light bulbs with an average lifespan of 800 hours and a standard deviation of 50 hours. What is the probability that a bulb lasts longer than 850 hours?
Use the complement rule for values greater than the calculated Z-score.
Given a normally distributed variable representing heights of adult men with a mean of 70 inches and a standard deviation of 3 inches, what percent of men are shorter than 66 inches?
Again, refer to Z-tables for cumulative probabilities for this Z-score.
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