Binomial Distribution Interview Questions
Binomial distribution interview prep for fixed independent trials, exact success counts, biased coins, approximations, and common mistakes.
Candidates practicing repeated independent trial questions for quant interviews.
Fixed number of trials
Binomial reasoning applies when there are n independent trials, each with the same success probability p, and the question asks about the number of successes.
Exact k successes
The probability of exactly k successes is C(n,k)p^k(1-p)^(n-k). The combination chooses which trials succeed; the probability term gives each such sequence probability.
Concrete example
For three flips of a biased coin with heads probability 0.4, the chance of exactly two heads is C(3,2)(0.4)^2(0.6).
Compare to geometric
Binomial fixes the number of trials and counts successes. Geometric waits until the first success. Choose the distribution from the question structure.
Approximations
For large n, normal or Poisson approximations may be useful under the right assumptions. In interviews, state why the approximation is appropriate before using it.
Common mistakes
Candidates use binomial formulas when trials are not independent or success probability changes. Check identical independent trials first.
Practice the pattern
Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.