The drug successfully treats 90% of cases. Calculate the probability that he will cure at least 18 patients out of 20?

Correct answer:

P =  67.6927 %

Step-by-step explanation:

p=90%=10090=0.9  C18(20)=(1820)=18!(2018)!20!=212019=190  p18=(1820) p18 (1p)2=190 0.918 (10.9)20.2852 C19(20)=(1920)=19!(2019)!20!=120=20  p19=(1920) p19 (1p)1=20 0.919 (10.9)10.2702 C20(20)=(2020)=20!(2020)!20!=11=1  p20=(2020) p20 (1p)0=1 0.920 (10.9)00.1216  P=100 (p18+p19+p20)=100 (0.2852+0.2702+0.1216)=67.6927%

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