Basics of Probability and Statistics Week 1 Challenge

1ans). population variance refers to the value of variance that is caculated from population data, and sample variance is calucaluted from sample data. due to this value of denominator in the formula for the variance in the case of sample data is 'n- 1' , and it is 'n' for the popuplation data.As a result both variance and standard deviation dervied from sample data are more than those found out from population data.

2 ans). In cluster sampling, the sampling is done on a population of clusters therefore, cluster/group is considered as a sampling unit.It is only selected clusters are sampled. The aim is to reduce cost and increase the efficiency of sampling.

In Stratisfied sampling, only selected cluster are sampled. In this sampling from each stratum a random sample is selected. The motive is to increase precision to reduce error.

3 ans). There are total no. cards =52

So total no. of possible outcomes, n(S) =52

Event of getting no. of jacks n(E) = 2

P(getting 2 jacks ) =n(E)/n(S)

= 2/52

= 1/26,,

4 ans). The total no. of possible outcomes n(S)= 36

The no of favourable outcomes n(E) = 6

P( getting same no. on both dice) = n(E)/n(S)

= 6/36

= 1/6

5 ans). Standard deviation is defined as the root of the mean square deviation.It is denoted as 'σ' and it is perfect indicater of the observation in the data set.

It is defined in numerical value, It is nothing but the average taken out of the squared deviation. It is denoted as 'σ2'.It is perfect indicator of the induvidual spread out in a group.