Help

#1
Hello I am new to talkstats. I could really use some help with a problem. I totally do not understand the Chebyshev's Theorem. It goes completely over my head when trying to break down a problem to apply it. Please help. Here is my problem,
A nationwide test taken by high school sophomores and juniors has three sections, each scored on a scale of 20 to 80 . In a recent year, the national mean score for the writing section was 50.2. Based on this information, complete the following statements about the distribution of the scores on the writing section for the recent year.

According to Chebyshev's Theorem, at least _% of the scores lie within 3 standard deviations of the mean, 50.2.

Suppose the distribution is bell shaped. If approximately 95% of the scores lie between 29.6 and 70.8, the approximate value of the standard deviation for the distribution, according to the empirical rule, is __? :confused:, :( Please, anybody. thank you.