Question

Suppose two drugs are routinely used for the treatment of thyroid dysfunction. Drug X is known to cure the disorder 75% of the time and costs $88. Drug Y is known to cure the disorder 60% of the time and costs $75. The two drugs work independent of each other. The two treatment plans are as follows:

Plan A: Treatment with Drug X—if not effective, treatment with Drug Y
Plan B: Treatment with Drug Y—if not effective, treatment with Drug X
1
Select the correct answer.
For what part of the population is Plan B NOT effective?
A.
40%
B.
30%
C.
15%
D.
10%

Answer 1

Alright I'd say u wanna focus on these parts 'Drug X is known to cure the disorder 75% of the time and costs $88. " and "Plan A: Treatment with Drug X—if not effective, treatment with Drug Y"

Now drug (X) could be non-effective with drug Y

So i'd say there is a 1% chance that it won't work with drug Y.

(U need to be keeping the percentage (1) the same)

U now wanna (Divide) (75%) by (100)

\[75\div100=0.75\]

Now (Subtract) (0.75) from (1)

\[1-0.75=0.25\]

Lets Focus on these parts now "Drug Y is known to cure the disorder 60% of the time and costs $75." and "Plan B: Treatment with Drug Y—if not effective, treatment with Drug X"

Drug (Y) could be non-effective with drug X

So as said before there is a (1%) chance that it won't work with drug X

(U can keep the (1) the same)

U know wanna (Divide) (60%) by (100)

\[60\div100=0.6\]

Now (Subtract) (0.6) from (1)

\[1-0.6=0.4\]


Now u wanna (Multiply) (0.25) by (0.4)


\[0.25\times0.4=0.1\]


U know wanna (Multiply) (0.1) by (100)


\[0.1\times100=10\]


So answer option D.)10% would be correct.