Q1)
a)
Ans. ii Density of people per square kilometer
Reason: We know that the variable means any characteristic, number, or quantity that can be measured or counted, hence, we can say that the variable would be â€œDensity of people per square kilometerâ€ as it will contain the data for Density of people per square kilometer.
b)
Ans. iii Set of densities of people per square kilometer of all countries
Reason: We know that the population is a set of similar items or events which is of interest for some question or experiment form this population we can select the sample for 56 countries to find the estimate of the population.

Q2)
a)
Ans. (iii) ordinal
Reason: Interval has equal meaning between each value, like temperature. Good and Excellent and Fair to Good don't have equal meaning. Nominal have no value applied, and the stars do. Ratio is a special case of interval where 0 matters. Whereas, ordinal means ordering of the data i.e. good, better, and best, we can see best is ordered with superiority.
b)
Ans. (i) cluster
Reason: We know that the cluster sampling is accomplished by dividing the population into groups and here we are dividing the research into different groups based on the psychology program, communications program, and cyber security program.

Q3
a)
Ans. True
Response: If the standard deviation is zero this means means there is no deviation in the observations from mean which explains that all the observations are same.
b)
Ans. False
Response: For normal distribution curve the mean, median and mode are same and we know that the center of the normal curve is mean which cannot be zero

2 1.The World Health Organization wishes to estimate the mean dens...