Two different types of alloy, A and B, have been used to manufacture experimental specimens of a small tension link to be used in a certain engineering application. The ultimate strength (ksi) of each specimen was determined, and the results are summarized in the accompanying frequency distribution.

.....................A ...................B

26 - < 30 .........6 ....................4

30 - < 34 ........12.................... 9

34 - <38 .........15.................. 19

38 - < 42.........7................... 10

..............m = 40 ..................m = 42

Compute a 95% CI for the difference between the true proportions of all specimens of alloys A and B that have an ultimate strength of at least 34 ksi.