Can anyone look over my answers for the following questions and let me know if they are correct or how I can fix them so I can get the best mark possible. My assessment is due in 3 days, and I am worried that the answers are incorrect. My answers are in bold.
Q1. For optimal fish growth and activity, the mean dissolved oxygen level in the water should be at least 5.0 parts
per million (ppm). To assess the health of a particular stream for supporting aquatic life, dissolved oxygen was
measured in 10 samples taken downstream from a sewerage treatment plant.
The measurements (in ppm) are given below. Note sample mean = 4.85 and s = 0.30.
Measurements (in ppm): 4.47 4.90 5.12 4.60 5.38 4.97 4.39 4.92 4.95 4.84
a) Create a 90% confidence interval for the actual mean dissolved oxygen level of the stream.
The 90% confidence interval is (4.69 – 5.01)
b) Explain in context what your interval means.
The confidence interval means that it is with 90% confidence that the actual mean dissolved oxygen level of the stream is between 4.69 and 5.01, based on only 10 samples.
c) Perform a hypothesis test to find out if the mean dissolved oxygen is significantly less than 5 ppm. Use a significance level of 5% and give your conclusion in plain English.
THE PICTURE ABOVE IS TAKEN FROM MY WORD DOCUMENT
Q3.
What is the effect of concussion on brain size? Researchers measured the brain sizes (hippocampal volume in
microliters) of 25 football players with a history of medically diagnosed concussion and 25 football player who
did not have any history of concussion. The data are summarised below.
a) Are the mean brain sizes for footballers from the two concussion groups significantly different? Carry out a hypothesis test. Use a significance level of 5% and use df = n1+n2-2.
It is concluded that the two concussion groups are not significantly different. The degrees of freedom is 46.
THE PICTURE IS TAKEN FROM MY WORD DOCUMENT.
b) Create a 95% confidence interval for the mean difference in brain size, and interpret the interval.
The confidence interval means that it is with 95% confidence that the mean difference in brain size is between 2.01 and 185.52.
c) Does the confidence interval confirm your answer to a)? Explain.
The confidence interval shows that my answer to a) is incorrect, as there is a difference in the mean sizes that are significant.
The feedback is much appreciated
Q1. For optimal fish growth and activity, the mean dissolved oxygen level in the water should be at least 5.0 parts
per million (ppm). To assess the health of a particular stream for supporting aquatic life, dissolved oxygen was
measured in 10 samples taken downstream from a sewerage treatment plant.
The measurements (in ppm) are given below. Note sample mean = 4.85 and s = 0.30.
Measurements (in ppm): 4.47 4.90 5.12 4.60 5.38 4.97 4.39 4.92 4.95 4.84
a) Create a 90% confidence interval for the actual mean dissolved oxygen level of the stream.
The 90% confidence interval is (4.69 – 5.01)
b) Explain in context what your interval means.
The confidence interval means that it is with 90% confidence that the actual mean dissolved oxygen level of the stream is between 4.69 and 5.01, based on only 10 samples.
c) Perform a hypothesis test to find out if the mean dissolved oxygen is significantly less than 5 ppm. Use a significance level of 5% and give your conclusion in plain English.
THE PICTURE ABOVE IS TAKEN FROM MY WORD DOCUMENT
Q3.
What is the effect of concussion on brain size? Researchers measured the brain sizes (hippocampal volume in
microliters) of 25 football players with a history of medically diagnosed concussion and 25 football player who
did not have any history of concussion. The data are summarised below.
| GROUP | MEAN | STANDARD DEVIATION |
| CONCUSSION GROUP | 5819 | 597.2 |
| NON-CONCUSSION GROUP | 6377 | 709.8 |
It is concluded that the two concussion groups are not significantly different. The degrees of freedom is 46.
THE PICTURE IS TAKEN FROM MY WORD DOCUMENT.
b) Create a 95% confidence interval for the mean difference in brain size, and interpret the interval.
The confidence interval means that it is with 95% confidence that the mean difference in brain size is between 2.01 and 185.52.
c) Does the confidence interval confirm your answer to a)? Explain.
The confidence interval shows that my answer to a) is incorrect, as there is a difference in the mean sizes that are significant.
The feedback is much appreciated