Answered: Suppose that an accounting firm does a…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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Question

Suppose that an accounting firm does a study to determine the time needed to complete one person's tax forms. It randomly surveys 100 people. The sample mean is 22.4 hours. There is a known population standard deviation of 6.4 hours. The population distribution is assumed to be normal.

NOTE: If you are using a Student's t-distribution, you may assume that the underlying population is normally distributed. (In general, you must first prove that assumption, though.)

1. In words, define the random variables X and X

- X is the number of tax forms that an accounting firm completes, and X is the mean number of tax forms that an accounting firm completes.

-X is the time needed to complete one person's tax forms, and X is the mean time needed to complete tax forms from a sample of 100 customers.

-X is the number of tax forms that an accounting firm completes, and X is the mean number of tax forms that an accounting firm completes.

2. If the firm did another survey, kept the error bound the same, and only surveyed 49 people, what would happen to the level of confidence? Why?

-The level of confidence would be larger because we have collected a smaller sample, obtaining less accurate information.

-The level of confidence would be smaller because we have collected a smaller sample, obtaining less accurate information.

-There would be no change.

3. Suppose that the firm decided that it needed to be at least 96% confident of the population mean length of time to within one hour. How would the number of people the firm surveys change? Why?

-The number of people surveyed would decrease because more accurate information requires a smaller sample.

-The number of people surveyed would increase because more accurate information requires a larger sample.

-There would be no change.

Features Features Normal distribution is characterized by two parameters, mean (µ) and standard deviation (σ). When graphed, the mean represents the center of the bell curve and the graph is perfectly symmetric about the center. The mean, median, and mode are all equal for a normal distribution. The standard deviation measures the data's spread from the center. The higher the standard deviation, the more the data is spread out and the flatter the bell curve looks. Variance is another commonly used measure of the spread of the distribution and is equal to the square of the standard deviation.

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