In rural China, children on average spend 3 hours per day unsupervised. Suppose that the standard deviation is 1.5 hours, and the amount of time spent alone is normally distributed. We randomly surveyed one Chinese child and found that this child spends 4.25 hours per day unsupervised.
a. How far away from the mean (indicate if the child is above or below the mean) is this child in terms of standard deviations?
b. What is the probability that a child spends more than 4.25 hours per day unsupervised?
c. What is the probability that a child spends less than 1 hour per day unsupervised?
d. How many hours per day are children unsupervised if they are in the 70% percentile? (Hint: You will need to convert the z-score into an x-score.)
Sample Solution
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