Question

It is generally claimed that the average body temperature for healthy human adults is 98.6°F. To test this claim a simple random sample of 9 adults are chosen. The average temperature of the 9 adults is only 98.1°F with a SD of 0.9°F. The question is whether the data on these 9 people is sufficient evidence to conclude that average body temperature among all healthy adults is really lower than 98.6°F. Assume the average body temperatures follow the normal curve.
1. Which significance test should be used?
a. z-test because the 50 of the population is known.
b. t-test because the SD of the population is known.
c. neither since it is untkely that temperatures would follow the nermal curve.
d. a t-test because the 50 of the sample is unknown.
e. a t-test because the SD of the pepulation is unknown.
Since the sample size is small and temperatures are lkely to be normaly distributed ether test may be used.
2. What is the null hypothesis?
A. That the average temperature in the population is 98.1 F.
B. That the average temperature in the pepulation is 98.6.
C. That the average temperature in the population is less than 98.6 F.
D. That the average temperature in the sample is 98.1.
3. What is the abernative hypothesis?
A. That the average temperature in the pepulation is 98.1 F.
B. That the average temperature in the population is 98.6F.
C. That the average temperature in the population is less than 98.6.
D. That the average temperabure in the sample is 98.17.
4. Compute SD.
5. Compute the best statistic.
6. How many degrees of freedom are there?

Answer 1

Answer:

Explained below.

Step-by-step explanation:

The information provided is as follows:

$\mu=98.6^{o}F\\\bar x=98.1^{o}F\\s=0.9^{o}F\\n=9$

(1)

A single mean test is to be performed in this case.

As the population standard deviation is not provided, a one-sample t-test will be used.

The correct option is b.

(2)

The null hypothesis is:

H₀: The average temperature in the population is 98.6°F, i.e. μ = 98.6°F.

The correct option is b.

(3)

The alternative hypothesis is:

Hₐ: The average temperature in the population is less than 98.6°F, i.e. μ < 98.6°F.

The correct option is c.

(4)

The standard deviation of the sample mean is as follows:

$SD_{\bar x}=\frac{s}{\sqrt{n}}=\frac{0.9}{\sqrt{9}}=0.3^{o}F$

Thus, the value of SD is 0.3°F.

(5)

Compute the value of test statistic as follows:

$t=\frac{\bar x-\mu}{SD_{\bar x}}$

  $=\frac{98.1-98.6}{0.3}\\\\=-1.666666667\\\\\approx -1.67$

Thus, the value of test statistic is -1.67.

(6)

The degrees of freedom of the test are:

df = n - 1

   = 9 - 1

   = 8

Thus, the degrees of freedom of the test is 8.