Question

1) Which of the following statements is correct about the standard normal distribution and t distribution?

a) standard normal distribution is used to eliminate population mean, while t distribution is used to estimate population standard deviation

b) t distribution is always centered at 0, while the center of a standard normal destruction depends on the sample mean

c) none of the 3 answer choices

d) standard normal distribution curve is higher than t distribution curve at the tails

2) If we know the population standard deviation and use sample mean to estimate the population mean, which of the following statements is correct?

a) it is not affected by our sample mean

b) it is smaller if we use a higher level of confidence

c) it may be larger or smaller than the size of confidence interval, depending on the confidence level

d) it is larger if our sample size is bigger

Answer 1

1)C is correct option.

None of the 3 answer choices are correct.

The normal distribution is used when the population distribution of data is assumed normal. It is characterized by the mean and the standard deviation of the data. A sample of the population is used to estimate the mean and standard deviation.
The t statistic is an estimate of the standard error of the mean of the population or how well known is the mean based on the sample size.

t distribution is higher at tails.

In 2 please mention what is the meaning of 'it' in the options.Otherwise the correct option cannot be chosen.