A student measured the lead content of a paint sample 4 times. the standard deviation of the measurements was found to be 1.1% of the average. can this student be 90% confident that the true value is within 1.8% of the measured average?

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Juliette Wells

Mathematics

20 February, 02:49

A student measured the lead content of a paint sample 4 times. the standard deviation of the measurements was found to be 1.1% of the average. can this student be 90% confident that the true value is within 1.8% of the measured average?

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Lyric Hale · Answer 1

yes. 1.8% is 1.8/1.1 = 1.64 standard deviations from the mean. So looking at the table of standard deviation and confidences, I see for the 90% value a value of 1.644854Ď which is slightly higher than the computed value of 1.64. So yes, the student can be 90% confident that the true value is within 1.8% if the measured average.