The national mean for verbal scores on an exam was 428 and the standard deviation was 113. Approximately what percent of those taking this test had verbal scores between 315 and 541 ? 17 A 68.2% B 52.8% C 38.2% D 26.4%

In a normal curve, the percentage of the scores between one and two standard deviations above the mean is approximately __________.   Select one: a. 14% b. 50% c. It is impossible to tell. d. 2% Clear my choice

The mean score on a set of 17 tests is 82. Suppose two more students take the test and score 66 and 56. What is the new​ mean?

Can someone please help? Thank you.

Levels of a certain enzyme in the blood have a mean value of 34.0 mg/mL and a standard deviation of 3.5 mg/mL.  Complete the following steps to determine what levels of the enzyme correspond to the top 20% of test results.   Are you calculating the top or bottom 20%? Answer So, which percentage needs to be converted to an area? Answer What is the area that you will look for in the table (four decimal places)? Answer What area will you actually use from the table (four decimal places)? Answer What is the z-score associated with that area (two decimal places)? Answer What is the cutoff level of the enzyme that corresponds to the top 20% of test results? (round to the nearest tenths)   Answer Are values lower or higher than that value also in the top 20%? Answer