The printed output of some computer-driven printers can be recognized by forensic analysts. The "Acme Model 200" printer was manufactured using two different inking mechanisms, one of which yields a "Type A" micropattern of ink spray around its characters. Of all Acme Model 200 printers, 70% produce this Type A micropattern, which is also characteristic of some models of other printers. Forensic analysts at a crime lab have been examining a kidnap ransom note which clearly exhibits the Type A micropattern.

Question

Quizplus · Accepted Answer

We know from the third sentence that the Type A micropattern exists in 70% of all Acme Model 200 printers and in some other models of printers. However, we know neither how many other models nor what percentage of other models produce the Type A micropattern. Hence, the probability that the note was printed on the Acme Model 200 printer cannot be determined. For that reason, responses A, B, C, and D are incorrect because the probability is based only on the characteristic of the one model printer that we know, the Acme Model 200, and not on all of the printer models that contain the Type A micropattern.

The Printed Output of Some Computer-Driven Printers Can Be Recognized