Help me out with this please?

A drug trial is testing the effectiveness of two drugs. If 30 patients are given Drug A, 10 patients are given Drug B, and 90 patients are given a placebo, what is the probability that a patient will not be given a placebo ?

A. 4/13
B. 3/13
C. 9/13
D. 1/13

Please give letter answer with response to why.

Question

Help me out with this please?

A drug trial is testing the effectiveness of two drugs. If 30 patients are given Drug A, 10 patients are given Drug B, and 90 patients are given a placebo, what is the probability that a patient will not be given a placebo ?

A. 4/13
B. 3/13
C. 9/13
D. 1/13

Please give letter answer with response to why.

anonymous · Answer

Just find a common denominator and add them together, then simplify.

jagr2713 · Answer

30 + 10 = 40 
 = 90+10+30 = 130 
= 40/1130 = 4/13. So, answer is A

anonymous · Answer

Thanks.

jagr2713 · Answer

Your're welcome