Beyond Common Core
Problem 33 of 45s12-033
Clinic wait times are right-skewed, mean 20 min, SD 12 min. How likely is a random sample of 36 waits to have a mean over 23 min? Area left of : ; : ; : .
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Solution walkthrough2:19
- One wait is right-skewed, with mean 20 min and SD 12 min. A sample of 36 waits gives one sample mean .
- Central limit theorem: with , is close to normal even though one wait is skewed.
- Mean of : . SD of : min.
- Turn 23 into a -score on the narrow curve: .
- Left of is . Over 23 min is the right tail: .
- Traps: is the left side, divides by , and divides by the variance 4.