Question

9.)The actual weight of 2-pound sacks of salted peanuts is found to be normally distributed with a mean
equal to 2.04 pounds and a standard deviation of 0.25 pounds. Given this information, the probability of a
sack weighing more than 2.40 pounds is 0.4251. **TRUE OR FALSE??**


13.)A university computer lab manager wishes to estimate the mean time that students stay in the lab per
visit. She believes that the population standard deviation would be no larger than 10 minutes. Further, she
wishes to have a confidence level of 90 percent and a margin of error of ± 2.00 minutes. Given this, the
sample size that she uses is approximately 60 students.
**TRUE OR FALSE?**

Answer 1

Check 9) using z-scores:

z = (x - mean)/sd
z = (2.40 - 2.04)/0.25
z = 1.44

Using a z-table, probability = 0.0749

Answer: False

Check 13) using margin of error:

Margin of error = z-value * (sd/√n)

2.00 = 1.645 (10/√n)
n is approximately 68 (rounded up)

Answer: Maybe true (depends on how close you want to approximate).