Math Problem Statement
A recent study has shown that a new treatment cures a certain disease 81% of the time. A random sample of 11 patients undergoing this treatment is chosen. Find the probability that 8 or 9 of them are cured.
Do not round your intermediate computations, and round your answer to three decimal places.
Solution
This problem can be approached using the binomial probability formula, which is:
where:
- (the number of patients),
- is the number of patients we want to find probabilities for (8 and 9, in this case),
- (the probability of a single patient being cured),
- is the binomial coefficient, which calculates the number of ways to choose cured patients out of total patients.
To solve the problem, we need to calculate and , then add these probabilities together.
Step 1: Calculate
- Binomial coefficient:
- Probability term for :
Step 2: Calculate
- Binomial coefficient:
- Probability term for :
Step 3: Add and
Now, calculate both probabilities and add them up:
After performing these calculations (using exact values for accuracy in intermediate steps), round the final answer to three decimal places.
Let's calculate it fully:
Calculation:
Final Answer:
The probability that exactly 8 or 9 out of the 11 patients are cured is approximately:
Would you like further details or have questions about any steps?
- What is a binomial probability distribution?
- How is the binomial coefficient calculated?
- What does it mean when we add probabilities for two values?
- Can this process be applied to other probabilities?
- What would happen if we increased the probability of success to 90%?
Tip: In binomial problems, always check if events are independent and only have two outcomes per trial.
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Math Problem Analysis
Mathematical Concepts
Probability
Binomial Distribution
Formulas
Binomial probability formula: P(X = k) = (n choose k) * p^k * (1 - p)^(n - k)
Binomial coefficient formula: (n choose k) = n! / (k!(n - k)!)
Theorems
Binomial Theorem
Suitable Grade Level
Grades 11-12
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