Answer:
10.3
Step-by-step explanation:
When calculating the mean from a grouped frequency table, first you must estimate what the value is through finding the number halfway between the value that x is greater than and less than:
The number halfway between 8 and 9 is 8.5
The number halfway between 9 and 10 is 9.5
The number halfway between 10 and 11 is 10.5
The number halfway between 11 and 12 is 11.5
Next, you have to multiply the estimated value by its frequency:
8.5 x 3 = 25.5
9.5 x 11 = 104.5
10.5 x 17 = 178.5
11.5 x 9 = 103.5
Then, add up the values you calculated and divide them by the total frequency (all the frequencies added up).
total estimated length: 25.5 + 104.5 + 178.5 + 103.5 = 412
total frequency: 3 + 11 + 17 + 9 = 40
412/40 = 10.3
