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Question 1 of 9 This question: 2 point(s) possible Approximationg the mean and standard deviation Class intervals Frequency 0-under 10 30 Given the following frequency distribution for n = 100. 10-under 20 10 20-under 30 30 a. Approximate the mean. 30-under 40 10 b. Approximate the standard deviation. 40-under 50 20 100 a. X= (Type an integer or a decimal.) b. S = (Round to two decimal places as needed.)