The Novelty Toy Company randomly selected 21 bags of marbles produced by its aut
ID: 3120294 • Letter: T
Question
The Novelty Toy Company randomly selected 21 bags of marbles produced by its automatic bagging machine. The numbers of marbles are given below.
Determine the mean of the number of marbles per bag.
X (No. of marbles)
X2
84
7056
87
7569
83
6889
85
7225
89
7921
83
6889
82
6724
87
7569
86
7396
86
7396
85
7225
84
7056
87
7569
88
7744
82
6724
84
7056
85
7225
86
7396
87
7569
86
7396
82
6724
Sum of x =1788
Sum of x2 = 152318
84.94
85.04
85.14
85.24
For the previous marble bagging problem determine the standard deviation of the number of marbles per bag.
1.93
2.03
2.13
2.23
Determine the interval for the marble count into which 95% of the bags will fall (m = xbar ± z*s). Use the Standard Normal table(Appendix C page 612) or Excel to find the appropriate z value. That is the z-value that covers 47.5% in the table (95% / 2 = 47.5%).
Lower = 80.1 Upper = 89.125
Lower = 81.1 Upper = 88.125
Lower = 81.0 Upper = 88.125
Lower = 81.1 Upper = 89.125
X (No. of marbles)
X2
84
7056
87
7569
83
6889
85
7225
89
7921
83
6889
82
6724
87
7569
86
7396
86
7396
85
7225
84
7056
87
7569
88
7744
82
6724
84
7056
85
7225
86
7396
87
7569
86
7396
82
6724
Sum of x =1788
Sum of x2 = 152318
Explanation / Answer
Answer to the problem:
1.
Sum of x =1788
n = 21
Mean = 1788/21 = 85.14
Option 3 is right
2.
Option 2 is the right answer. 2.03
3.
That' =85.14+-1.96*2.03 or option 4
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