Military intelligence units are often responsible for intercepting and deciphering coded messages used be enemy forces. In this type of work, time is critically important. Recently the army compared two methods of deciphering coded messages. Two special agents randomly assigned 49 random selected messages to two groups, and used identical computers to decode the messages. One of them used Deiphermatic (sample 1) to decode 24 messages and the other used QuickDecipher (sample 2) to decode 25 messages. The means and standard deviations for the time required by the computer, in minutes to decode the messages are given in the minitab output below.

Two-Sample T-Test and CI Sample N Hean St DEY SE Mean 24 37.48 8 . 16 1.7 25 31.02 3. 68 0.74 Difference = mu (1) - m (2) Estimate for difference: 6.46 95% CI for difference: (2.75, 10. 17) T-Test of difference = 0 (vs not =): T-Value = 3.55 p-Value=0. 001 DF=31