Statistics Cheat Sheet

Good Essays
What proportion of a normal distribution is located in the tail beyond z = +2.00?
0.0228
What proportion of a normal distribution is located between the mean and z = 1.40?
0.4192
The Z-score corresponding to the 52nd percentile is
.05
A normally distributed variable has a mean of 10 and a standard deviation of 2. The probability that a value between 7 and 9 is obtained is
.2417
An accelerated life test on a large number of type-D alkaline batteries revealed that the mean life for a particular use before they failed is 19.0 hours. The distribution of the lives approximated a normal distribution. The standard deviation was 1.2 hours. About 95.44% of the batteries failed between what two values?
16.6 & 21.4
The average time students need to finish a particular test is 70 minutes with a standard deviation of 12 minutes. (Assume that these times are normally distributed.) If we want 90% of the students to have sufficient time to finish the test, how much time should we give them?
85.36 minutes
The distribution of sample means will be normal if either the population is normal or if the sample size is greater than 30.
Increasing the alpha level (for example, from α=0.01 to α= 0.05)
Increases the probability of a Type I error.
Increases the size of the critical region.
Increases the probability that the sample will fall into the critical region.
Samples of size n = 16 are selected from a population with μ= 80 with σ= 16. What is the standard error for the distribution of sample means?
4
The Intelligence Quotient (IQ) test scores for adults are normally distributed with a mean of 100 and a standard deviation of 15. What is the probability we could select a sample of 50 adults and find that the mean of this sample is less than 95?
0.0091
Which of the following accurately describes a hypothesis test?
An inferential technique that uses the data from a sample to draw inferences about a population.
What is measured by the denominator of the z-score test statistic?
The

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