Basics of Probability and Statistics Week 1 Challenge

# Question 1

We are taking only a small set of data from population as a sample. In calculating a variance of sample to get a higher variance, we need to use (n-1) which is a lower number results in higher variance. The higher variance would be slightly near to variance of population.

# Question 2

stratified sampling:

Stratified sampling is a technique in which data is splitted into starts or groups of certain characteristics and sample would be taken from each groups.

Example: From a population ABCDEFG of ABC:DEF:GHI > BDI were taken as a sample using stratified sampling.

Cluster sampling is the technique in which the population are divided into clusters / different groups and all elements in one particular cluster were taken into an occur as sample.

Example: From a population ABCDEFG of ABC:DEF:GHI > ABC were taken as a sample using cluster sampling.

# Question 3

If population (n),(r) number of samples we can create n!/r!(n-r)!.

# Question 4

4c2/52c2-> 1/221

# Question 5

6/36-> 1/6

# Question 6

Variance would allow us to calculate the dispersion of data. The dispersion value can be any negative or positive values, so inorder to convert the negative value into positive, we square the dispersion values. In this case the units will also get squared. Inorder make the consistency of units in dispersion values we calculate standard deviation which is nothing but a square root of variance.