Nt1310 Unit 3 Assignment

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ANSWERS TO STA10003 Mid-Unit Test

Question 1:

a. The Protein Additive
b. Chicken shell thickness
c. The method used is Experimental, because the researcher manipulated the protein additive intake.
d. The research hypothesised is that the shell thickness of the chickens with protein additive added to their feed, would be thicker than the regular fed chickens.
e. All egg producers
f. p= 0.555
g. The sample means does not differ significantly because the p value is higher than 0.05
h. The 95% interval indicates that the mean shell thickness is between 0.60mms to 1.10mms more than protein fed chicken
eggs.

i. FORMAL REPORT:
It was suggested that chickens fed protein additive would produce eggs with thicker shells than regular fed chickens.
In a sample of 49 chicken, the average shell thickness for regular fed chickens.
( mms ,mms, ) was greater than the average protein additive fed chickens (, mms,). However, an independent samples t-test shows that this difference in mean shell significance is not significant,, p = .555. The 95% confidence interval indicates that, on average, shell thickness is between .60mms less and 1.10mms more in the regular fed chickens than the chickens fed protein additive.
There is insufficient evidence to suggest that chickens fed protein additive produce thicker egg shells than regular fed chickens.

Question 2:

a. The price is not unusual, the price falls within the likely range. It is within 2 standard deviations of the mean price.
b. Z= (3200-3750)/250=(-550)/250= -2.2
c. Both prices are unusually high, however the z scores show the Australian engagement ring priced at $4400 is unusually higher than a ring priced at $4800 in the US. z=(4400-3750)/250=(650/250)= 2.6 ($4400 AUD is 2.6 SD above the mean.
Z=(4800-4500)/125=(300/125)=2.4 ($4800 USD is 2.4 SD above the mean.

Question 3:

a. Kwik Kofi home market coffee machines
b. The highlighted section represents all of the samples of 30 of 1500 espresso shots in which the proportion is 30.03%.

!
c. If you are unable to draw / move the arrow,  then use the spacebar to move the ! to the desired placement

d. Yes, the sample complies with the sample distribution in figure 1 as it falls within 2 standard deviations of the mean.
e. Sample sizes of size 200 with a mean of 29.97 would be quite common if the population mean was 30ml. The sample is consistent with a population where the mean espresso shot is 30ml.
f. Binomial test

Question 4:

a. All adults
b. Yes, the sample selection is biased. The patients selected were only from the Eye and Ear Hospital.
c. The repeated measures design
d. Vitamin A intake
e. Patient age and varied supplement Vitamin A absorption, however this is controlled by randomly selection of patients.
f. There is no confounding factors evident in the description of this experiment. Only visual acuity differs systematically over the two groups.
g.
h.
Question 5:

a. All Australian Adults
b. The 95% confidence interval indicates that between 44% - 52% of Australian adults consume at least 1 hamburger a week.

c. A researcher in the Australian Health System hypothesised that the percentage of 51% of Americans consume more than one hamburger a week is an overestimation of Australian adults. In a random sample of 491 Australian adults, 48% consumed more than one hamburger a week. While this is slightly lower than percentage of Americans hamburger consumption (51%), a binomial test shows that the difference is not significant, n=491, p=.122. The 95% confidence interval indicates that between 44% and 52% of Australian Adults consume more that one hamburger a week.
There is insufficient evidence to suggest that the percentage of Australian adults who consume at least one hamburger a week is an overestimation.