Question

QUESTION 7 

In a clinical study, volunteers are tested for a gene that has been found to increase the risk for a disease. The probability that a person carries the gene is 0.1. Ten people are tested what is the probability that 3 or more people are found to have the gene?

a. Approx. 7.0296 

b. Approx. 92.98% 

c. Approx. 98.72% 

d. None of the above 

QUESTION 8 

In a clinical study, volunteers are tested for a gene that has been found to increase the risk for a disease. The probability that a person carries the gene is 0.1. What is the probability that the 6^th  individual test is the FIRST person with the gene in question?

a. Approx. 7.0296 

b. Approx. 92.98% 

c. Approx. 98.72% 

d. None of the above 

Answer 1

#7.
p = 0.1

P(X >= 3) = 1 - P(X <3)
= 1 - P(X = 0) - P(X = 1) - P(X = 2)
= 1 - (1 - 0.1)^10 - 10C1*0.1*0.9^9 - 10C2*0.1^2*0.9^8
= 1 - 0.9298
= 0.0702

approx. 7.02%

#8.
Required probability = 0.9^5*0.1 = 0.0590

Approx 6%