In April 2025
Search & Filtering
INTERVAL ESTIMATE
4. Suppose that the amount of time spend by working student weekly is normally distributed with the standard deviation of 25 minutes. A random sample of 125 observations is drawn and the sample mean is computed as 150 minutes. Determine the 95% confidence interval estimate of the population mean.
The Average weight of 25 chocolate bars selected from a normally distributed population is 200 grams with a standard deviation of 10 grams. Find the point estimate and the confidence interval using 95%confidence level.
Steps: Solution:
1.Describe the population parameter of The parameter of interest is the
interest. ________________(1)of the
weight of chocolate bars.
A perfectly competitive firm has a domestic demand curve is P=100. This firm's total cost function is TC=2Q^2+20Q. Costs and prices are in ethiopian birr. Based on this information
a) drive the revenue function
b) calculate the equilibrium level of output, and profit?
c) calculate shutdown level of output, and profit?
d) calculate the break even level of output , and profit?
INTERVAL ESTIMATE
4. Suppose that the amount of time spend by working student weekly is normally distributed with the standard deviation of 25 minutes. A random sample of 125 observations is drawn and the sample mean is computed as 150 minutes. Determine the 95% confidence interval estimate of the population mean.
SAMPLE SIZE DETERMINATION
3. A bread shop owner wishes to find the 95% confidence interval of the true mean cost of special bread. How large should the sample be if she wishes to be accurate within ₱8? As previous study showed that the standard deviation of the price was ₱12.
Many manufacturing problems involve the matching of machine parts, such as shafts fit into a
valve hole. A particular design requires a shaft with a diameter of 22.00mm, but shafts with
diameters between 21.99mm and 22.02mm are acceptable. Suppose that manufacturing
process yields shafts with diameters normally distributed, with a mean of 22.002mm and a
standard deviation of 0.005 mm. For this process,
a. What is the proportion of shafts with a diameter between 21.99 mm and 22.00 mm?
b. What is the probability that a shaft is acceptable?
c. Find what is diameter that will be exceeded by only 5 percent of the shafts?
d. What would be your answers in (a) through (c) if the standard deviation of the shaft
diameters were 0.004 mm?
Directions: identify the test tool use in a certain problem
1. Hospital Infections A medical investigation claims that the average number of infections per week at a hospital in south-western Pennsylvania is 16.3. A random sample of 10 weeks had a mean number of 17.7 infections. The sample standard deviation is 1.8. Is there enough evidence to reject the investigator's claim at alpha = 0.05 ?
Type of test:
Reason/s:
Suppose a ∈ Z. If a
2 − 6a + 5 is even, then a is odd. (Use Proof by Contrapositive)
manufacturer of cables has developed a high tension steel cable 1 cm. in diameter which is claimed to have an average breaking strength of 1,800 kg. A sample of 16 cables is found to have an average breaking strength of with a standard deviation s = 100 kg. Test the manufacturer’s claim using . Pertinent hypotheses are the following:
H0:μ = 1800 kg
Ha:μ ≠ 1800 kg
What is the computed value of appropriate test statistic?
The average zone of inhibition (in mm) for mouthwash L as tested by the medical
technology students has been known to be 9mm. A random sample of 10 mouthwash L was
tested and the test yielded an average zone of inhibition of 7.5mm with a variance of 25
mm. Is there enough reason to believe that the anti-bacterial property of the mouthwash
has decreased? Test the hypothesis that the average zone of inhibition of the mouthwash is
no less than 9mm using 0.05 level of significance.
A. State the hypotheses.
B. Determine the test statistic to use.
C. Determine the level of significance, critical value, and the decision rule.
D. Compute the value of the test statistic.
E. Make a decision.
F. Draw a conclusion.
