t-distribution

In the absence of the population variance and/or if the sample size is small, which sampling distribution is being used?

• chi distribution
• p-distribution
• t-distribution
• z-distribution

Who developed the t-distribution in 1908?

• William S. Gosset
• Wilhem G. Student
• Ronald A. Fisher
• a student from Gosset Academy

When do we say that the sample size is sufficiently large?

• When it is greater than or equal to 10.
• When it is greater than or equal to 20.
• When it is greater than or equal to 30.
• When it is greater than or equal to 40.

In Student’s t-distribution, if the sample size is 25, what is the degree of freedom?

• 5
• 24
• 25
• 26

How does t distribution differ from a normal distribution?

• The t-distribution has a thicker tail.
• The t-distribution has a higher peak.
• The t-distribution is centered at 0.
• The t-distribution is symmetric in the middle.

When do you use t-distribution instead of normal distribution?

• When the sample size is less than 30.
• If the sample standard deviation is unknown
• If the population standard deviation is known
• When the sample size is greater than or equal to 30

The CEO of Flying Fire Corporation claims that an average Flying Fire light bulb lasts 300 days. A researcher randomly selects 15 bulbs for testing. The sampled bulbs last an average of 290 days, with a standard deviation of 50 days. Identify the population mean.

• 300 days
• 290 days
• 50 days
• 15 bulbs

The CEO of Flying Fire Corporation claims that an average Flying Fire light bulb lasts 300 days. A researcher randomly selects 15 bulbs for testing. The sampled bulbs last an average of 290 days, with a standard deviation of 50 days. What is the number of degrees of freedom?

• 299
• 289
• 49
• 14

• 1.17
• 1.1
• 1.04
• 1.01

Which property of t-distribution is also a property of normal distribution?

• In t-distribution, the variance is always greater than 1.
• In t-distribution, the standard deviation is always greater than 1.
• The tails of the t-distribution curve are asymptotic to the horizontal axis.
• The shape of the t-distribution curve depends on the degrees of freedom.