Final answer:
To express '5 less than 3 times a number' algebraically, it is written as '3x - 5', where 'x' is the unknown number.
Step-by-step explanation:
To write '5 less than 3 times a number', you need to express this relationship using algebra. Let's denote the unknown number as 'x'. Three times a number would be '3x'. To express '5 less than' this quantity, you subtract 5 from 3 times the number. Therefore, expressed algebraically, '5 less than 3 times a number' is written as '3x - 5'.
Understanding this concept involves recognizing that subtraction changes the sign of the number being subtracted before operating the addition or subtraction. For example, if you were to subtract 3 from 5, it would be written as '5 - 3' which equals 2. Similarly, '5 less than 3 times a number' maintains the structure with the variable representing the number.
The Positive Predictive Value (PPV) in this medical scenario is 67%, indicating that when the test identifies a patient as requiring further investigation for alcohol use, there is a 67% chance the patient does indeed have a problem with alcohol use.