What effect does standardizing into z-scores have on the spread (standard deviation) of a variable?

The annual per capita consumption of oranges (in pounds) in the United States  can be approximated by a normal distribution. The mean annual per capita  of oranges is 19.2 with a standard deviation of 4 pounds.  what annual per capita consumption of oranges represents the 5th percentile?

True or False? Assume a researcher recruits 150 African American and Caucasian individuals taking warfarin to determine if there is a difference in the mean dosage of the medication needed to cause a decrease in their INR blood test. If the mean dosage for 75 Caucasian individuals required to get their INR blood test in range is 6.1 mg with a standard deviation of 1.7 mg and the mean dosage for 75 African American individuals required to get their INR blood test in range is 4.3 mg with a standard deviation of 0.9 mg, the S p value obtained while calculating the test statistic is approximately 1.14 mg.  True  False

College students average 8.2 hours of sleep per night with a standard deviation of 45 minutes. If the amount of sleep is normally distributed, what proportion of college students sleep for more than 9 hours? Probability = %3D