just answer is fine, I am for checking my work.

In interval estimation, the t distribution is applicable only when*

the population has a mean less than 30

the variance of the population is known

the mean of the population unknown

the sample standard deviation is used to estimate the population standard deviation

In point estimation*

a data from the population is used to estimate the population parameter

data from the sample is used to estimate the population parameter

data from the sample is used to estimate the sample statistics

the mean of the population equals the mean of the sample

A random sample of 64 students at a university showed an average age of 25 years and a sample standard deviation of 2 years. The 98% confidence interval for the true average age of all students in the university is*

20.5 to 29.5.

24.4 to 25.6.

23.0 to 27.0.

20.0 to 30.0.

The standard deviation of a sample of 200 elements taken from a very large population is determined to be 50. The variance of the population*

can no be larger than 60

can to be larger than 3600

must be at least 100

can be any value greater or equal to zero.

For the interval estimation of when is known and the sample is large, the proper distribution to use is the*

t distribution with n degrees of freedom

t distribution with n + 1 degrees of freedom.

normal distribution

t distribution with n - 1 degrees of freedom.