A study was conducted in a large population of adults concerning eyeglasses for correcting reading vision.Based on an examination by a qualified professional,the individuals were judged as to whether or not they needed to wear glasses for reading.In addition it was determined whether or not they were currently using glasses for reading.The following table provides the proportions found in the study. What is the probability that a selected adult is judged to need eyeglasses but does not use them for reading?
A)0.42
B)0.18
C)0.54
D)0.60
E)0.36

Question

A study was conducted in a large population of adults concerning eyeglasses for correcting reading vision.Based on an examination by a qualified professional,the individuals were judged as to whether or not they needed to wear glasses for reading.In addition it was determined whether or not they were currently using glasses for reading.The following table provides the proportions found in the study.  What is the probability that a selected adult is judged to need eyeglasses but does not use them for reading?
A)0.42 
B)0.18 
C)0.54 
D)0.60 
E)0.36

Quizplus · Accepted Answer

The probability that a selected adult is judged to need eyeglasses is 0.7 (given in the table). The probability that the selected adult who needs eyeglasses does not use them for reading is 0.26 (also given in the table). Therefore, the probability that a selected adult is judged to need eyeglasses but does not use them for reading is the product of these two probabilities: 0.7 x 0.26 = 0.182 or approximately 0.18. So, the best choice is B.

A Study Was Conducted in a Large Population of Adults