problem

[medphys]

Dear users

How can I solve these two problems by SAS software.

1.   A normally distributed random variable has an unknown mean Pand a known variance V2= 9. Find
the sample size required to construct a 95 percent confidence interval on the mean, that has total width of
1.0. 

2. A new filtering device is installed in a chemical unit. Before its installation, a random sample
yielded the following information about the percentage of impurity: y1= 12.5, S12=101.17   (variance S1), and n1= 8.
After installation, a random sample yielded y2= 10.2, S22= 94.73  (variance S2)   , n2= 9.

(a) Can you concluded that the two variances are equal? Use D= 0.05.

(b) Has the filtering device reduced the percentage of impurity significantly? Use D= 0.05.

Best regards

[PeterClemmensen]

What have you tried yourself so far?

[medphys]

Nothing

[Reeza]

1. PROC POWER

2. PROC ANOVA/TTEST but I'm not familiar with D, so thats something unique that your field is using.

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@medphys wrote:

Dear users

How can I solve these two problems by SAS software.

1.   A normally distributed random variable has an unknown mean Pand a known variance V2= 9. Find
the sample size required to construct a 95 percent confidence interval on the mean, that has total width of
1.0. 

2. A new filtering device is installed in a chemical unit. Before its installation, a random sample
yielded the following information about the percentage of impurity: y1= 12.5, S12=101.17   (variance S1), and n1= 8.
After installation, a random sample yielded y2= 10.2, S22= 94.73  (variance S2)   , n2= 9.

(a) Can you concluded that the two variances are equal? Use D= 0.05.

(b) Has the filtering device reduced the percentage of impurity significantly? Use D= 0.05.

Best regards

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