Student Loans According to a 2016 report from the Institute for College Access and Success 66 % of all graduates from public colleges and universities had student loans. A public college surveyed a random sample of 400 graduates and found that 62 % had student loans. a. Test the hypothesis that the percentage of graduates with student loans from this college is different from the national percentage. Use a significance level of 0.05. b. After conducting the hypothesis test, a further question one might ask is what proportion of graduates from this college have student loans? Use the sample data to find a 95 % confidence interval for the proportion of graduates from the college who have student loans. How does this confidence interval support the hypothesis test conclusion?
Student Loans According to a 2016 report from the Institute for College Access and Success 66 % of all graduates from public colleges and universities had student loans. A public college surveyed a random sample of 400 graduates and found that 62 % had student loans. a. Test the hypothesis that the percentage of graduates with student loans from this college is different from the national percentage. Use a significance level of 0.05. b. After conducting the hypothesis test, a further question one might ask is what proportion of graduates from this college have student loans? Use the sample data to find a 95 % confidence interval for the proportion of graduates from the college who have student loans. How does this confidence interval support the hypothesis test conclusion?
Solution Summary: The author explains how to determine a test hypothesis for the percentage of graduates with student loans from the college.
Student Loans According to a 2016 report from the Institute for College Access and Success
66
%
of all graduates from public colleges and universities had student loans. A public college surveyed a random sample of 400 graduates and found that
62
%
had student loans.
a. Test the hypothesis that the percentage of graduates with student loans from this college is different from the national percentage. Use a significance level of
0.05.
b. After conducting the hypothesis test, a further question one might ask is what proportion of graduates from this college have student loans? Use the sample data to find a
95
%
confidence interval for the proportion of graduates from the college who have student loans. How does this confidence interval support the hypothesis test conclusion?
3. Bayesian Inference – Updating Beliefs
A medical test for a rare disease has the following characteristics:
Sensitivity (true positive rate): 99%
Specificity (true negative rate): 98%
The disease occurs in 0.5% of the population.
A patient receives a positive test result.
Questions:
a) Define the relevant events and use Bayes’ Theorem to compute the probability that the patient actually has the disease.b) Explain why the result might seem counterintuitive, despite the high sensitivity and specificity.c) Discuss how prior probabilities influence posterior beliefs in Bayesian inference.d) Suppose a second, independent test with the same accuracy is conducted and is also positive. Update the probability that the patient has the disease.
4. Linear Regression - Model Assumptions and Interpretation
A real estate analyst is studying how house prices (Y) are related to house size in square feet (X). A simple
linear regression model is proposed:
The analyst fits the model and obtains:
•
Ŷ50,000+150X
YBoB₁X + €
•
R² = 0.76
• Residuals show a fan-shaped pattern when plotted against fitted values.
Questions:
a) Interpret the slope coefficient in context.
b) Explain what the R² value tells us about the model's performance.
c) Based on the residual pattern, what regression assumption is likely violated? What might be the
consequence?
d) Suggest at least two remedies to improve the model, based on the residual analysis.
5. Probability Distributions – Continuous Random Variables
A factory machine produces metal rods whose lengths (in cm) follow a continuous uniform distribution on the interval [98, 102].
Questions:
a) Define the probability density function (PDF) of the rod length.b) Calculate the probability that a randomly selected rod is shorter than 99 cm.c) Determine the expected value and variance of rod lengths.d) If a sample of 25 rods is selected, what is the probability that their average length is between 99.5 cm and 100.5 cm? Justify your answer using the appropriate distribution.
Chapter 8 Solutions
Pearson eText Introductory Statistics: Exploring the World Through Data -- Instant Access (Pearson+)
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, statistics and related others by exploring similar questions and additional content below.
Discrete Distributions: Binomial, Poisson and Hypergeometric | Statistics for Data Science; Author: Dr. Bharatendra Rai;https://www.youtube.com/watch?v=lHhyy4JMigg;License: Standard Youtube License