Question

In a normal bell shaped curve, approximately which percentage of scores fall within 3 standard deviation (-3 to +3) or blank (34%,68%,95%,99%) of all scores

Answer 1

Let x represent the scores. With mean and standard deviation given,

The Empirical rule states that

1) About 68% of the x values lie between 1 standard deviation below and above the mean

2) About 95% of the x values lie between 2 standard deviation below and above the mean

3) About 99.7% of the x values lie between 3 standard deviation below and above the mean

If we consider this rule, then the percentage of scores that fall within 3 standard deviation (-3 to +3) is 99% because this is closer to 99.7%