A survey of senior citizens at a doctor's office shows that 45% take blood pressure-lowering medication,41% take cholesterol-lowering medication,and 14% take both medications.What is the probability that a senior citizen takes either blood pressure-lowering or cholesterol-lowering medication?
A)0.18
B)0.72
C)0.00
D)1.00
E)0.86

Question

Quizplus · Accepted Answer

To find the probability that a senior citizen takes either blood pressure-lowering or cholesterol-lowering medication, we need to add the probabilities of taking each medication and then subtract the probability of taking both medications to avoid double counting. 
P(taking blood pressure-lowering medication) = 0.45 
P(taking cholesterol-lowering medication) = 0.41 
P(taking both medications) = 0.14 
P(taking either medication) = P(taking blood pressure-lowering medication) + P(taking cholesterol-lowering medication) - P(taking both medications) 
= 0.45 + 0.41 - 0.14 
= 0.72 
So, the probability that a senior citizen takes either blood pressure-lowering or cholesterol-lowering medication is 0.72.

A Survey of Senior Citizens at a Doctor's Office Shows