There are three measures of center: mean, median, and mode.
The median would be the number in the middle when the numbers are ordered. 35 45 45 60 60 70 80
The mode would be the number that occurss most frequently. Since 45 and 60 both appear twice, you take the mean of the two, which is 52.5
The mean would be the sum of all the numbers divided by the amount of numbers. 60+70+45+60+80+35+45 = 395/7 ≈ 56.43 You could really justify any of these, but typically you would use the mean in this case because there are no outliers.
The measure of center is mean. You would be finding the average number of minutes spent studying. To find the mean of the data you would add all of the numbers up and divide by the total amount of numbers you added. 60+70+45+60+80+35+45 =395 395/7 =<span>56.4285714286</span>
