Standard deviation (50 points) dr. cwetna recorded all of the grades on a unit test on the chart below. what is the mean and standard deviation of the distribution of individual grades? (18 points) 1. = . = identify the following and label the dot-plot above (4 points each) 3. = and 4. = and 5. = and find the percentage of test scores within each range listed above. 6. (4 points) does the data indicate a normal distribution? 7. (6 points) why or why not? 8. (10 points) we want to know the probability that a student selected randomly from her class would have an “a” (90 or above) in her class. find the probability. explain how to find the probability