math word problem help

Question

The Nevada Gaming Commission gives 250 polygraph tests each month to potential casino employees. On average, 4% of the applicants are former criminals who are trying to hide their identity. The polygraph test is 90% accurate.

a. How many of the former criminals will make it through the polygraph test without being caught?
b. How many applicants that are not lying will be falsely accused?

Answer 1

The Nevada Gaming Commission gives 250 polygraph tests each month to potential casino employees. On average, 4% of the applicants are former criminals who are trying to hide their identity. The polygraph test is 90% accurate.

.04(250) = 10 former criminals

Therefore, 240 non-criminals

 

.10(10) = 1 former criminal who will make it through

.10(240) = 24 innocent folk who will appear to be lying. 

 

this is why polygraphs are not admissible in court.