Basics of Probability and Statistics Week 1 Challenge

Q1. Why there is a difference in the formula of variance for population and sample

Ans. Population variance refers to the value of variance that is calculated from population data, and sample variance is the variance calculated from sample data. Due to this value of denominator in the formula for variance in case of sample data is 'n-1', and it is 'n' for population data.

Q2. Difference between stratified and clustered sampling

Ans. Relatedly, in cluster sampling you randomly select entire groups and include all units of each group in your sample. However, in stratified sampling, you select some units of all groups and include them in your sample. In this way, both methods can ensure that your sample is representative of the target population.

Q3. How many different samples can be created out of population of size n

Ans. Answer and Explanation: The size of the sample to be taken is equal to the size of the population. This means that the number of different random samples that can be taken is 1

Q4. What is the probability of drawing 2 jacks from a pack of card.

Ans. At 52 cards drawn the probability is 1.0.

Q5. What is the probability that both the numbers on dice are same while rolling 2 dice

Ans. The probability of getting the same number of both the dice is 1/6.

Q6. Why standard deviation when variance can measure the dispersion in data.

Ans. Standard deviation measures how far apart numbers are in a data set. Variance, on the other hand, gives an actual value to how much the numbers in a data set vary from the mean. Standard deviation is the square root of the variance and is expressed in the same units as the data set.