Basics of Probability and Statistics Week 1 Challenge

Q1 In case of skewed data the sample variance and population variance vary a lot from each other. In order to solve this problem the experimentation has been done and instead of dividing by n the researchers divided by (n-1), (n-2) and so. It was then found out that when divided by n-1 the sample variance and population variance was very similar. So that why there is a difference in the formula of variance for population and sample.

Q2 In cluster sampling we randomly select entire groups and include all units of each group in our sample. However, in stratified sampling we select some units of all groups and include them in our sample. In this way both methods can ensure that our sample is representative of the target population.

Q3 The different samples that can be created out of population of size n are

(2^n)-1

Q4 The probability of drawing 2 jacks from a pack of card is

=(4/52)*(3/51)
=1/221

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

=6/36

=1/6

Q6 A variance is used to measure how far the data values are dispersed from the mean, and the standard deviation is used to calculate the amount of dispersion of the given data set values.