In a Random Sample of 25 Calls Made from the U.S.to

question 5

Multiple Choice

In a random sample of 25 calls made from the U.S.to Japan by callers using Skype during the past week, the average call lasted 21.4 minutes, with a sample standard deviation of 5.1 minutes.Assume the population distribution of call times is normal.Build a 99% confidence interval estimate of the average call time for the population of calls represented by the sample (that is, the population of all calls made from the US to Japan last week by callers using Skype) .Report the upper bound for your interval.

• A)25.91
• B)25.16
• C)23.16
• D)24.25
• E)22.87

---

Definitions:

Transcription Factors

Proteins that regulate the transcription of genes by binding to DNA sequences.

Humus

Organic matter in various stages of decomposition in the soil; gives soil a dark brown or black color.

Prop Root

An adventitious root that arises from the stem and provides additional support for a plant such as corn.

Buttress Root

A bracelike root at the base of certain trees that provides upright support.