http://www.ck12.org Chapter 6. Measures of Central Tendency - Basic
TABLE6.3:
Time (Hours) Tally Number of Students
12 /// 3
15 // 2
20 /// 3
8 //// 4
25 // 1
11 /// 3
14 /// 3
18 /// 3
13 /// 3
28 / 1
5 // 2
24 / 1
16 / 1Now that the frequency for each value has been determined the mean can now be calculated:
Solution:
x ̄=∑
x 1 f 1 +x 2 f 2 +x 3 f 3 +...+xnfn
f 1 +f 2 +f 3 +...+fnx ̄=12 ( 3 )+ 15 ( 2 )+ 20 ( 3 )+ 8 ( 4 )+ 25 + 11 ( 3 )+ 14 ( 3 )+ 18 ( 3 )+ 13 ( 3 )+ 28 + 5 ( 2 )+ 24 + 16
3 + 2 + 3 + 4 + 1 + 3 + 3 + 3 + 3 + 1 + 2 + 1 + 1
x ̄=429
30
x ̄= 14. 3The mean amount of time that each student spends using a cell phone is 14.3 hours.
Now we will return to the problem that was posed at the beginning of the lesson –the one that dealt with hand spans.
TABLE6.4:
Hand span (inches) Frequency
612 1
714 3
712 8
734 10
814 7
812 4
914 2Solution: