MATH 214 Probability and Statistics for Business

Dr. Ed Donley

Computer Assignment 4

Section 004: Due Monday, April 30, 2001

Section 007: Due Tuesday, May 1, 2001

On January 29, 1986, the space shuttle Challenger exploded and seven American astronauts died. Experts agreed that the disaster was caused by two leaky O-rings. Prior to the flight, some rocket engineers had theorized that the O-rings would not seal properly due to the cold weather. The predicted temperature at launch time was 26^oF to 29^oF. The engineers based their theory on data collected on O-ring damage and temperatures for all 23 previous space shuttle launches. These data are given in the spreadsheet at

http://www.ma.iup.edu/~hedonley/ma214/oring.xls

The O-ring damage index is a measure of the total number of incidents of O-ring erosion, heading and blow-by. [Report of the Presidential Commission on the Space Shuttle Challenger Accident, Washington, D.C., 1986, Vol. II, pp. H1-H3 and Vol. IV, p. 664. Post-Challenger Evaluation of Space Shuttle Risk Assessment and Management, Washington, D.C., 1988, pp 135-136.]

A) Use Excel to construct a linear regression line for predicting the O-ring damage index from the flight time temperature. Plot the data points and the regression line.

B) What is the predicted O-ring damage index for a flight time temperature of 28^oF? Do you trust this predicted value? Why?

C) Attempt to demonstrate, with a hypothesis test, that O-ring damage will increase as flight time temperature decreases. Use a = 0.05.

D) Construct a 90% confidence interval for the O-ring damage index for a flight time temperature of 28^oF.