PROJECT 6: PROBABILITY

Individual Project

Measurement data are taken continually on the production lines of a company producing hot rolled carbon steel rods. On one line, which produces 1 1/4 inch diameter rods in 10 foot lengths, monitoring the diameter indicates that the the average size is 1.250 inch and the data is normally-distributed with a standard deviation of 0.00540 inch.

The company must reject those rods whose diameters lie outside the tolerance range of +/- 0.011 inch as specfied by AISI.

  1. What percentage must be rejected?
  2. New readings are taken at a rate of 20 per hour. What would you expect the sample mean and standard deviation of the 20 readings to be if no statistical changes occur?
  3. During an 8 hour shift sample averages (of 20 readings each) were made as listed in the table below. Check on the table whether each one lies within or outside 3 (sample) standard deviations above or below the expected sample mean.
  4. What percentage of the sample means are expected to lie within the +/- 3 sigma band.

Average within outside
1.2485 X
1.2481 X
1.2506 X
1.2503 X
1.2490 X
1.2544
X
1.2553
X
1.2546
X

Due:Monday, Mar 24 5:30 PM

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