Question

ATCs are required to undergo periodic random drug testing.

Answer 1

Answer:

The responsess to the given question can be defined as follows:

Step-by-step explanation:

$P(medication\ used) = 0.007 \\\\P( drug \not\ used ) = 1 - 0.007 = 0.993\\\\P(test\ positive | medication \ used) = 0.96 \\\\ P(test \ negative | medication \ used) = 1 - 0.96 = 0.04$

$P(Point | Non-used\ medication )=0.93\\\\ P(Point |No\ medication ) = 1 - 0.93 = 0.07$

As per the given info we draw the tree diagram which is defined in the attachment file.

$P ( test \ is\ positive ) = P( medication \ used ) \times P( Test \ positive | medication \ used ) + P( medication not \ used ) \times P( Test\ positive | medication \ not \ used )$

                  $= ( 0.007 \times 0.96 ) + ( 0.993\times 0.07 )\\\\= 0.0762$

$P( medication \ used | test\ positive )= \frac{\textup{P( medication used ) *P( Test positive given medication used )}}{\textup{P( medication used )}}$  

$= \frac{( 0.007\times 0.96 )}{0.0762}\\\\= 0.0882$