A sales representative makes 6 cold calls in a day. The probability of successfully making a sale on any given call is 40%. Find the probability of making a sale on all 6 calls.
Table of contents
- 1. Introduction to Statistics53m
- 2. Describing Data with Tables and Graphs2h 1m
- 3. Describing Data Numerically1h 48m
- 4. Probability2h 26m
- 5. Binomial Distribution & Discrete Random Variables2h 55m
- 6. Normal Distribution & Continuous Random Variables1h 48m
- 7. Sampling Distributions & Confidence Intervals: Mean2h 8m
- 8. Sampling Distributions & Confidence Intervals: Proportion1h 20m
- 9. Hypothesis Testing for One Sample2h 23m
- 10. Hypothesis Testing for Two Samples3h 25m
- 11. Correlation1h 6m
- 12. Regression1h 4m
- 13. Chi-Square Tests & Goodness of Fit1h 30m
- 14. ANOVA1h 4m
5. Binomial Distribution & Discrete Random Variables
Binomial Distribution
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A biologist is monitoring a large bird sanctuary where a particular bird species is known to have a 70% success rate for each nesting attempt (at least one chick fledges from the nest). This season, she observes 500 independent nesting attempts across the sanctuary.
(A) What is the probability that exactly 450 nesting attempts are successful?
A
3.54×10−78
B
0.70
C
3.3×10−27
D
1

1
Step 1: Recognize that this is a binomial probability problem. The binomial distribution is used when there are a fixed number of independent trials (n), each with two possible outcomes (success or failure), and a constant probability of success (p). Here, n = 500, p = 0.7, and we are looking for the probability of exactly 450 successes.
Step 2: Use the binomial probability formula: P(X = k) = (n choose k) * p^k * (1-p)^(n-k). Here, X is the random variable representing the number of successes, k is the desired number of successes (450), n is the total number of trials (500), and p is the probability of success (0.7).
Step 3: Calculate the binomial coefficient (n choose k), which is given by the formula: (n choose k) = n! / [k! * (n-k)!]. Substitute n = 500 and k = 450 into this formula.
Step 4: Substitute the values into the binomial probability formula. Raise p (0.7) to the power of k (450) and (1-p) (0.3) to the power of (n-k) (50). Multiply these results by the binomial coefficient calculated in Step 3.
Step 5: Use a calculator or statistical software to compute the final probability value. Note that due to the large numbers involved, it is often more practical to use logarithms or software to handle the calculations efficiently.
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