Statistics and Probability Answers

The value of a single sample statistic, which is used to represent the true, but unknown value of a population parameter, is known as a ______. Select one:

a. standard error

b. confidence interval estimate

c. proportion

d. point estimate

The________of a confidence interval is a measure of its precision. Select one:

a. length

b. variance

c. width

d. diameter

Whenever the population standard deviation is unknown, when computing confidence intervals, it is usually estimated by the ________. Select one:

a. median of the distribution

b. sample standard deviation

c. variance

d. mode of the distribution

A car is driven 20,000 km/year. To test the claim, a sample at 150 car owners are picked randomly and asked to state the distance that their car had traveled in a year. Do you agree to the claim of the following sample data: x = 22,500 km, σ = 3800 km. Use the significance level of 5%.

Show working on critical value approach and p-value approach.

Assume that when adults with smartphones are randomly​ selected, ​64% use them in meetings or classes. If 9 adult smartphone users are randomly​ selected, find the probability that exactly 2 of them use their smartphones in meetings or classes.

Assume that one adult was smart phones are randomly selected 64% use them in meetings are classes if not adult smart phone users are randomly selected find the probability that exactly 2 of them use their smart phones in meetings or classes

Based on the concept on testing the difference between two independent means using t-test and the learning exercises that you have done, write your arguments or lessons learned below.

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4.

5.

Getting acquainted with the essential terms and concepts on testing the difference between two independent sample means using t-test, it is now time for you to explain thoroughly your answers to the following questions.

1. Explain the role of the following statistical terms in testing the difference of two independent samples using t-test.

a. Hypotheses (Null and Alternative Hypotheses)

b. Test of significance (One Tailed Test and Two Tailed Test)

c. Level of significance 

d. Critical region 

e. Critical value 

f. Test value 

Use the traditional method in testing the hypothesis in the problems below.

a. State the hypotheses and identify the claim.

b. Find the critical value(s)

c. Find the test value

d. Make the decision

e. Summarize the result

2. A nurse was hired by a governmental ecology agency to investigate the impact of a lead smelter on the level of lead in the blood of children living near the smelter. Ten children were chosen at random from those living near the smelter. A comparison group of seven children was randomly selected from those living in an area relatively free from possible lead pollution. Blood samples were taken from the children and lead levels determined. The following are the results (scores are in micrograms of lead per 100 milliliters of blood):

Children living near smelter 18 16 21 14 17 19 22 24 15 18

Children living in unpolluted area 9 13 8 15 17 12 11 - - -

Analyze the result using two-tailed test with ∝= 0.10.