Standard x-ray machines should give radiation dosages below 5.00 mill roentgens (mil-r). To test a certain x-ray machine, a sample of 36 observations is taken with a mean of 4.13 mil-r and a standard deviation of 1.91 mil-r.
-How much evidence do we have that the machine is in specification?
A)No evidence
B)Some evidence
C)Strong evidence
D)Very strong evidence
E)Extremely strong evidence

Question

Quizplus · Accepted Answer

The sample mean is 4.13 mil-r, which is below the specification limit of 5.00 mil-r. Given the sample size of 36, the standard error is 1.91/sqrt(36) = 0.3183. The z-score is (4.13 - 5.00) / 0.3183 = -2.73, which indicates very strong evidence that the machine is in specification.

Standard X-Ray Machines Should Give Radiation Dosages Below 5