standard_description: Develop a probability distribution for a random variable defined for a sample space in which theoretical probabilities can be calculated; find the expected value. For example, find the theoretical probability distribution for the number of correct answers obtained by guessing on all five questions of a multiple-choice test where each question has four choices, and find the expected grade under various grading schemes.
problem_activity: Problem 1
Below is a normal distribution that shows the height of 8-year-old boys in inches. The relative frequency of each height is shown along the
$${y-}$$
axis, and the height, in inches, is shown along the
$${x-}$$
axis.
The mean is 50 and the standard deviation is 2.
[IMG]
Estimate the percent of 8-year-old boys chosen randomly who will be shorter than 53 inches.
Problem 2
The mean combined score for last year’s SAT was 1083 with a standard deviation of 193. The mean and the standard deviation are based on students who took the SAT across the nation.
If you took the SAT and scored a combined score of 1100, what percent of students who took the SAT scored below you?


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