Math Problem Statement

Imagine that you are applying for jobs. The probability that a submitted application yeilds an interview is 20%. If you apply for five jobs, what is the probability that you get less than two interviews?

Solution

To solve this problem, we can model it as a binomial distribution. In a binomial distribution, the probability of success (getting an interview) is p=0.2p = 0.2, and the probability of failure (not getting an interview) is 1p=0.81 - p = 0.8. You are applying for 5 jobs, so the number of trials is n=5n = 5.

We need to find the probability of getting less than two interviews, which means getting either 0 or 1 interview. This is the sum of the probabilities for 0 interviews and 1 interview.

The probability mass function (PMF) of a binomial distribution is given by:

P(X=k)=(nk)pk(1p)nkP(X = k) = \binom{n}{k} p^k (1 - p)^{n - k}

where:

  • nn is the number of trials,
  • kk is the number of successes (in this case, the number of interviews),
  • pp is the probability of success,
  • (nk)\binom{n}{k} is the binomial coefficient, representing the number of ways to choose kk successes from nn trials.

We need to calculate P(X=0)P(X = 0) and P(X=1)P(X = 1), then add them together.

Step 1: Probability of 0 interviews (X=0)(X = 0)

P(X=0)=(50)(0.2)0(0.8)5=11(0.8)5=0.32768P(X = 0) = \binom{5}{0} (0.2)^0 (0.8)^5 = 1 \cdot 1 \cdot (0.8)^5 = 0.32768

Step 2: Probability of 1 interview (X=1)(X = 1)

P(X=1)=(51)(0.2)1(0.8)4=50.2(0.8)4=50.20.4096=0.4096P(X = 1) = \binom{5}{1} (0.2)^1 (0.8)^4 = 5 \cdot 0.2 \cdot (0.8)^4 = 5 \cdot 0.2 \cdot 0.4096 = 0.4096

Step 3: Total probability

Now, we sum these probabilities to find the probability of getting less than two interviews:

P(X<2)=P(X=0)+P(X=1)=0.32768+0.4096=0.73728P(X < 2) = P(X = 0) + P(X = 1) = 0.32768 + 0.4096 = 0.73728

Thus, the probability of getting less than two interviews is approximately 0.737 or 73.7%.


Would you like further details or have any questions?

Here are 5 follow-up questions you might find interesting:

  1. What is the probability of getting exactly 2 interviews?
  2. How would the probability change if you applied for 10 jobs instead of 5?
  3. What is the expected number of interviews when applying for 5 jobs?
  4. How would the calculation change if the probability of an interview were 30% instead of 20%?
  5. Can we find the probability of getting at least one interview?

Tip: The binomial distribution is often used to model the number of successes in a fixed number of independent trials, such as flipping a coin or applying for jobs.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Probability
Binomial Distribution

Formulas

P(X = k) = \binom{n}{k} p^k (1 - p)^{n - k}
P(X < 2) = P(X = 0) + P(X = 1)

Theorems

Binomial Probability Theorem

Suitable Grade Level

Grades 10-12