Interview Q&A / Data Science

1. What is a z-score, and how does it help compare values on different scales?

   A z-score is (value - mean) / standard deviation, the number of standard deviations a value sits from the mean. Because it removes units and scale, you can compare a Maths mark with a Physics mark fairly.

   BeginnerQuick answer1 min read
2. What is the 68-95-99.7 rule for the normal distribution?

   In a normal distribution, about 68% of values lie within 1 standard deviation of the mean, 95% within 2 and 99.7% within 3. It gives a fast way to judge how unusual a value is.

   BeginnerQuick answer1 min read
3. When do you use the binomial distribution?

   Use it to count successes in a fixed number of independent trials, each with the same probability of success. The probability of exactly k successes in n trials is C(n,k) p^k (1-p)^(n-k).

   BeginnerQuick answer1 min read