Maths · Probability: Probability of an event, addition and multiplication theorems of probability
The average length of time required to complete a jury questionnaire is 40 minut
The average length of time required to complete a jury questionnaire is 40 minutes, with a standard deviation of 5 minutes. What is the probability that it will take a prospective juror between 30 and 50 minutes to complete the questionnaire?
- A. About \( 85 \% \)
- B. About \( 90 \% \)
- C. About \( 95 \% \)
- D. none
Step-by-step solution
Given a normal distribution with mean 40 minutes and standard deviation 5 minutes, the probability of a time between 30 and 50 minutes corresponds to values within 2 standard deviations of the mean. By the empirical rule, approximately 95% of data lies within 2 standard deviations, so the probability is about 95%.
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