Homework Assignment #3

Due October 22,2003

Textbook, pages 56-57

Problems numbers 1,3, and 5

 

1.                 Mass measurements on a run of large casting gave the following results.  Mass m is in kg.

165    166    186

201    200    190

152    180    175

159    199    190

200    177    165

200    190    170

 

Determine the mean, mode, and the standard deviation of the mass for these data.  Comment on the relative magnitudes of the mean and the mode.

 

3.            A random check is made on nominal 1-megaOhm resistors taken from a production batch.  The measured resistances R in megaOhms are:

1.476 1.392 1.280 1.205

              1.083 1.026 1.296 0.903

              0.934 0.853 0.842 1.543

              0.693 1.394 1.161 1.206

              1.616 1.186 1.071 0.923

Determine the mean resistance and the standard deviation for these data.

 

 

5.     Fatigue tests at constant stress have been conducted on samples of two titanium alloys, ten of the samples contain 1.5% vanadium, and the other twelve contain 2.0% vanadium  In other aspects, the samples are identical.  (Alloy 1.5V was analyzed in class)

Fatigue life in 10,000 hours:

Alloy 2.0V

              1.45

              1.60

              1.44

              1.40

              1.55

              1.62

              1.40

              1.50

              1.40

              1.58

              1.55

              1.49

Determine the mean, median, mode, and standard deviation of the fatigue life of this alloy.  Do you think there is a significant difference between the fatigue lives of this alloy and the one we analyzed in class based on the statistics?