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Material safety data sheets. The Occupational Safety &Health Administration has required companies that handle hazardous chemicals to complete material safety datasheets (MSDSs). These MSDSs have been criticized for being too hard to understand and complete by workers. A

study of 150 MSDSs revealed that only 11% were satisfactorily completed (Chemical & Engineering News, February7, 2005).

a. Give a point estimate of p, the true proportion of MSDSs that are satisfactorily completed.

b. Find a 95% confidence interval for p.

c. Give a practical interpretation of the interval, part b.

Short Answer

Expert verified

a. The point estimate of p is 0.11

b. The 95% confidence interval is0.06,0.16 .

c. This means that one can 95% confident that true value of population proportion lies in the interval0.06,0.16.

Step by step solution

01

Given Information

It is given that the survey conducted on Material Safety Data (MSD) by The Occupational Safety & Health Administration, is found to be tough to comprehend by the workers. Out of 150 MSDs, only 11% had been completed.

02

The point estimate of parameter p

a.

Here, MSDs stand for Material Safety Data. Therefore, the true proportion of MSDs that are satisfactorily completed is denoted by the point estimate . This value in question is given to be 11%.

Therefore, p^=0.11.

03

Find the 95% confidence interval 

The 95% confidence interval for proportion 鈥榩鈥 is denoted by the formula:

CI=p^zp^1-n

Now, =0.11,1-=0.89andn=150. Also, z value for 95% level of significance is 1.96.

Substituting we get,

CI=0.111.960.110.89150=0.110.05

Therefore, the confidence interval is 0.06,0.16.

04

Interpreting the interval

c.

The interval0.110.05encloses an unknown population parameter with a certain level of confidence that is 95%. This means that one can 95% confident that true value of population proportion lies in the interval0.06,0.16 .

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