To solve this level once type "answer" in your notepad. To solve twice type "the answer" in your notepad. To solve three times type "el answer" in your note pad and you will earn a gold star in this level.
Mean is calculated by adding the numbers, then divide by the count of numbers. The count is 3 in this case. 15 + 10 + 15 = 40, so mean = 40/3 = 13.3333.....
11.82 To find the mean of something, add all the figures and then divide by the number of figures. You would save youself time by just doing this in a calculator instead of posting it here.