Basics of Probability and Statistics Week 1 Challenge

1) The difference in formula of variance for population and sample is denominator N & N-1 because we want same value in both population and sample variance.

2) stratified sampling : when we select random data for ex : from one classroom i have to select 4 students so if i choose randomly to maintain proportion of 4 like select 2 boys 2 girls or 3 girls 1 boys or 3 boys 1 girls that type of slection called stratified selection

clustered sampling : when the selection of sample based on study the whole data and select equally type ,ex : if i select want to select 4 students then i will choose 2 girls ,2 boys that type of selecting sample called cluster sampling

3) (2**n) -1

4)4c2/52c2

5)6/36 =1/6

6)in variance we will get unit in sqaure term so we cant able to measur that unit that why we use standard deviation which is the `sqrtvariance`