A new drug shows promise in decreasing cholesterol. Marketing needs the average cholesterol reduction per patient with a margin of error of 4 units at 90% confidence. A preliminary study estimated the standard deviation at 16 units. What sample size is required

Q: The mean score in a test is normally distributed with mean 30 and standard deviation 10. What is…

A: Given :  Mean, μ = 30 standard deviation, σ = 10 x = 55

Q: The scores on a psychology test were normally distributed with a mean of 65 and a standard deviation…

A: According to empirical rule 68%,95% and 99.7% data fall within one ,two and three standard…