Basics of Probability and Statistics Week 1 Challenge

Q.1 difference between formala of variance for population and sample is:

population : `σ² = Σ (x_i – μ)² / N

sample : σ² = Σ (x_i – μ)² / N -1

Q.2

stratified sampling : In thiis type sample are picked from a sample of homogeneous group.

eg.A student council surveys 100100100 students by getting random samples of 252525 freshmen, 252525 sophomores, 252525 juniors, and 252525 seniors.

clustered : In this sample is selected form random groups or clusters

eg.An airline company wants to survey its customers one day, so they randomly select 555 flights that day and survey every passenger on those flights.

Q.3 Infinite

Q.4 1/221 or 0.0045 or .45%

Q.5 1/6

Q.6 One of the primary reasons is that the standard deviation is in the same unit as the original data, while the variance is in squared units. This makes the standard deviation more interpretable and easier to relate to the original data.

other reasons: the standard deviation is more sensitive to outliers than variance