Marci mailed nine letters at the post office. each letter weighed 3.5 ounces. what was the total weight of the letters

What is the standard deviation of the following data set rounded to the nearest tenth? 3, 17, 18, 15, 12, 21, 9

What is the remainder when 2872 is divided by 76? a) 51 b) 57 c) 60 d) 63

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.