SOLUTION: albino rats used to study the hormonal regulation of a metabolic pathway are injected with a drug that inhibits body synthesis of protein. Usually, 4 out of 20 rats die from the dr

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Question 1203266: albino rats used to study the hormonal regulation of a metabolic pathway are injected with a drug that inhibits body synthesis of protein. Usually, 4 out of 20 rats die from the drug before the experiment is over. This time round, 10 animals are treated with the drug. What is the probability that 5 of these animals will die before the expiriment is over?
Answer by ikleyn(52884) About Me  (Show Source):
You can put this solution on YOUR website!
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The binomial distribution with the number of trials n= 10;
probability of "success" in each individual trial p= 4%2F20 = 1%2F5 = 0.2;
and the number of "successful" trials k= 5.


Use the standard formula for the probability


   P = C%5B10%5D%5E5%2A0.2%5E5%2A%281-0.2%29%5E%2810-5%29 = %28%2810%2A9%2A8%2A7%2A6%29%2F%281%2A2%2A3%2A4%2A5%29%29%2A0.2%5E5%2A0.8%5E5 = 0.02642.   (rounded).    ANSWER

Solved.

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To see many other similar solved problems of this type,  look into the lessons
    - Simple and simplest probability problems on Binomial distribution
    - Typical binomial distribution probability problems
in this site.

Learn the subject from there.