A suitable probability calculator can tell you the probability is about 6.7%.
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The standard deviation of the distribution of sample means is the population standard deviation (6) divided by the square root of the sample size (√144=12). Thus, your threshold is about (19.25-20)/(6/12) = -1.5 standard deviations from the mean.
Answer:
Step-by-step explanation:
We have the following variables:
y: hours of sleep
x: age
Each day, a young person should sleep 9 hours
This means that y is 9 added to something
plus 1 4 hour for each year that the person is under 18 years of age.
For each year the person is under 18 years of age, she should sleep 1/4 = 0.25h on top of the 9 hours.
So the equation relating hours of sleep y and age x is: