Answer: 83.3
Step-by-step explanation:
Formula :
(1)
(2)
Given : In a psychology class, 32 students have a mean score of 93.2 on a test.
By Using (2) , Sum of scores of 32 students = 93.2 x 32 =2982.4 (3)
Then 16 have a mean score of 63.4.
Again, By Using (2) , Sum of scores of 16 students = 63.4 x 16 =1014.4 (4)
Total students = 32+16 = 48
Add (3) and (4) , we get combined score of 48 students = 2982.4+ 1014.4
=3996.8
Now , by using (2) , the mean score of all of these students together
Hence, the mean score of all of these students together is 83.3.
Answer:
7.5
Step-by-step explanation:
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Find the mean ( average):
105 + 104 + 110 + 112 + 114 + 106 + 108 +109 = 868
Mean = 868 / 8 = 108.5
Standard deviation:
108.5 - 105 = 3.5, 3.5^2 = 12.25
108.5 - 104 = 4, 4^2 = 16
110 - 108.5 = 1.5, 1.5^2 = 2.25
112 - 108.5 = 3.5, 3.5^2 = 12.25
114 - 108.5 = 5.5, 5.5^2 = 30.25
108.5 - 106 = 2.5, 2.5^2 = 6.25
108.5 - 108 = 0.5, 0.5^2 = 0.25
109 - 108.5 = 0.5, 0.5^2 = 0.25
12.25 + 16 +2.25 + 12.25 + 30.25 +6.25+0.25+0.25 = 79.75
79.75/8 = 9.96875, SQRT(9.96875) = 3.1573
Standard Deviation = 3.1573
108.8 +/- 1.96 *(3.1573/sqrt(8) = 110.687 and 106.312
110.687 - 108.5 = 2.19
108.5 - 106.312 = 2.19
Margin of error = +/- 2.19
