Elementary statistics – Final assignment – Part two
NOTE : Don’t use p-value for your decision in hypothesis testing problem

Q2: a) You are interested in the average emergency room (ER) wait time at your local hospital. You
take a random sample of 50 patients who visit the ER over the past week. From this sample, the
mean wait time was 30 minutes and the standard deviation was 20 minutes. Find a 95%
confidence interval for the average ER wait time for the hospital. Interpret your result.
b) An experiment was carried out in which the result can either be a “positive” reaction or a
“negative” reaction. If the probability of a positive reaction is 0.4 and the experiment is repeated 6
times,
i) what is the probability that the number of positive reactions will be 2 times
ii) what is the probability that the number of positive reactions will be At least 1 times

16. The following data are from an experiment comparing two treatments:

Assume that the data are from a repeated-measures experiment using the same sample of n = 5 subjects in both treatments. Calculate the difference score (D) for each subject and use the sample of difference scores to determine whether there is a significant difference between the two treatments. Again, use a two-tailed test with a = .05.

For the repeated measures analysis you did, which of the following is TRUE:

a.       the t you look up is on 8 degrees of freedom

b.      the t you compute is LESS than 2.776

c.       the treatment's effect is significant

d.      the treatment's effect is non-significant

Post-lab: Neutralization Power of an Antacid

1) This experiment used the technique of back titration. Describe the process of back titration in 2-3 sentences. Why is back titration used instead of directly titrating a solution of antacid with 0.15 M HCl?

2) Phenolphthalein is an indicator which turns a pink color at a pH of 8.3. In this experiment, phenolphthalein is added to the antacid solution to indicate the equivalence point of the back titration. Phenolphthalein solution by itself is weakly acidic. If instead of adding one drop, a student adds several milliliters of the phenolphthalein solution, will this cause the student to under-estimate or over-estimate the neutralizing power of the antacid?

3) The active ingredient in Philips Milk of Magnesia is Mg(OH)2, in Amphojel it is Al(OH)3, and in Alka-Seltzer it is NaHCO3. Write balanced equations showing how each neutralizes stomach acid.

1. A)
The freezing point of benzene, C₆H₆, is 5.500 °C at 1 atmosphere. K_f(benzene) = 5.12 °C/m

In a laboratory experiment, students synthesized a new compound and found that when 11.43 grams of the compound were dissolved in 267.0 grams of benzene, the solution began to freeze at 4.740 °C. The compound was also found to be nonvolatile and a non-electrolyte.

What is the molecular weight they determined for this compound?

____g/mol

B) The boiling point of benzene, C₆H₆, is 80.100 °C at 1 atmosphere. K_b(benzene) = 2.53 °C/m

In a laboratory experiment, students synthesized a new compound and found that when 10.44 grams of the compound were dissolved in294.0 grams of benzene, the solution began to boil at 80.412 °C. The compound was also found to be nonvolatile and a non-electrolyte.


What is the molecular weight they determined for this compound ?

____g/mol

2-2.  In the 1950’s Matthew Meselson and Franklin Stahl did an experiment in which they took bacteria that had grown for many generations in medium containing the stable nitrogen isotope 15N, and transferred them into medium containing only the 14N isotope of nitrogen.  They purified DNA from these bacteria at time zero (before transfer to 14N) and after 1 and 2 rounds of DNA replication in 14N medium.

1. When they analyzed the density of DNA molecules at time zero (before bacteria had been in the 14N medium), what did they observe?

2. When they analyzed the density of DNA molecules after one round of DNA replication, what did they observe?

3. When they analyzed the density of DNA molecules after two rounds of DNA replication, what did they observe?

4. What was the major conclusion from the Meselson-Stahl experiment?

An article in Solid State Technology, "Orthogonal design for process optimization and its application to plasma etching" by G.Z.Yin and D.W.
Jillie (May, 1987) describes an experiment to determine the effect of the
C2F6 flow rate on the uniformity of the etch on a silicon wafer used in
integrated circuit manufacturing. All of the runs were made in random order. Data for two flow rates are as follows:

C2F6     Uniformity Observation
Flow 1      2      3      4     5      6

125   2.7   4.6 2.6   3.0   3.2   3.8

200   4.6   3.4   2.9   3.5   4.1   5.1

a) Does C2F6 flow rate affect average etch uniformity? use a=0.05

b) What is the P-value for the test in part (a)

c)Does the C2F6 affect the wafer-to-wafer variability in each uniformity? use a0.05

d) Draw box plots to assist in the interpretation of the data from this experiment

“3. Would these conditions apply to all fungal growth? Why or why not?”

“4. How would changing the type of bread (fresh from a bakery, no preservatives vs. prepackaged with preservatives) affect the results? Describe an experiment that would test your hypothesis.”

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“5. How would changing the incubation temperature of the bags affect the results? Describe an experiment that would test your hypothesis.”

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“6. Look up the pH of lemon juice and vinegar. Based on your results and your knowledge of favorable environmental conditions for fungal growth, what can you conclude about the effect of pH on growth? How would making the pH more basic affect growth?”

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“7. What is the source of the mold that grew on the samples?”

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1. The experimental results in the table below represent real values from an experiment on the cat soleus muscle. For our purposes we will assume the muscle weighs 4 grams and is shaped like a cylinder that is 1 cm² in cross-sectional area.

2. a Draw and label the force-velocity curve for this muscle in the graph on the right. Make sure you label and scale all axes.

2b. Draw a second line that is the power-velocity curve. (Hint: watch your units here!!)

Please answer and draw both curves and give explanation. Will give great review.