# Thread: Hi guys need help with this question before my test tmw, help greatly appreciated

1. ## Hi guys need help with this question before my test tmw, help greatly appreciated

(a) For women aged 40-65, the prevalence rate of breast cancer is 800 pet 100,000. A particular
diagnostic test is accurate for 85% of women with breast cancer and for 95% of women
who do not have breast cancer.
(i) The diagnostic test is positive for a particular woman. What is the probability that
she has breast cancer?
(ii) Given a sample of n women, let X denote the number of women who have breats
cancer. State what the probability distribution of this random variable is, and justify
(iii) If 10,000 women were tested, how many would you expect to have breast cancer?

2. ## Re: Hi guys need help with this question before my test tmw, help greatly appreciated

Hey MathJack.

Can you show us what you have tried?

3. ## Re: Hi guys need help with this question before my test tmw, help greatly appreciated

for part a I got .5964. I used Bayes rule. Let P(T|A) = .85 and P(T|A') = .05, where T is to test positive and A to have breast cancer. The trick is to find P (A|T) i think.. which requires Bayes formula.

Not sure how to do the other parts