19. maximum mark: 1 23n.1.sl.tz0.28 what perc...
19. maximum mark: 1 23n.1.sl.tz0.28 what percentage of the normally distributed data lies within two standard deviations from the mean? a. 68% b. 75% c. 95% d. 98% 1 20. maximum mark: 1 23n.1.sl.tz0.29 a study monitored 100m performance time. initially, time was recorded using a stopwatch. during the study, the method was modified to use timing gates. which aspect of study design was enhanced? a. validity b. safety c. accuracy d. specificity 1
Answer
# Answer:
19. C. 95%
20. C. Accuracy
# Explanation:
## Step1: Recall normal - distribution property
In a normal distribution, approximately 95% of the data lies within two standard deviations of the mean. So for question 19, the answer is C.
## Step2: Analyze study - design change
Timing gates are more precise than stop - watches for measuring 100m performance time. This change in measurement method enhances the accuracy of the study. So for question 20, the answer is C.