Search & Filtering
Let X and Y be independent random variable with means 3 ,5 and variances 16,25 respectively. Find the mean and standard deviations of 5X-3Y?
I. Determine whether it is categorical, quantitative discrete, or quantitative continuous.
a. Technology ownership: Do you own a computer?
b. Time (per week in minutes) spent using a computer for writing documents (word processing).
c. Which social networking site(s) are you a member? (Facebook, Myspace, Friendster, etc.)
II. True or False
1. If the time to wait for pharmacy help has a uniform distribution from 0 minutes to 30 minutes, then 33% of the customers are expected to wait more than 20 minutes.
2. If X has a Binomial (50, 0.7) distribution, then the criteria to use the normal approximation are met.
b) ABC Ltd is evaluating to invest in two projects. Project X may yield a return of £1.5m with a probability of 20%, or a return of £5m with a probability of 60%. Project Y, instead, may earn a negative return of £3m with a probability of 70% or a positive return of £7m with a probability of 30%.
1) How much is the expected return for project X and Y?
2) What is the standard deviation?
3) Compare and briefly discuss the expected return and risk of the projects.
. Identify a research problem. Write the research questions and develop the theoretical model. Also identify and label the variables. Write down hypotheses as well.
Identify a research problem. Write the research questions and develop the theoretical model. Also identify and label the variables. Write down hypotheses as well.
To appreciate the different merits of observation in the field and observation in a controlled environment, read the scenarios below and answer the questions that follow.
Scenario 2. A usability consultant observes how participants perform a pre-planned task using the wearable navigation device in a usability laboratory. The task requires the participants to find the telephone number of a restaurant called Matisse. It takes them several minutes to do this and they appear to have problems. The video recording and interaction log suggest that the interface is very fiddly and the audio interaction is of poor quality, and this is supported by participants’ answers on a user satisfaction questionnaire.
1. What are the advantages and disadvantages of these two types of observation?
2. When might each type of observation be useful
Find the co-efficient of correlation between persons employed(X) and cloth manufactured(Y) in a textile Mill. Interpret the results.
X
137
209
113
189
176
200
219
Y
23
47
22
40
39
51
49
A study is conducted to compare the performance of students with more than one personal electronic gadget and those with only one. A few of them were taken as respondents for the study. The mean grades of these students and the standard deviations are shown below. Is it possible to conclude that there is no significant difference in the mean grades of the two types of students at a 95%
confidence level?
Students Mean Standard Deviation Sample Size
With one gadget x̅1 = 83 s1 = 12 n1 = 7
With more than one gadget x̅2 = 79 s2 = 13 n2 = 5
Given the population 2, 4, 8, 8, 10, 10. Draw a sample of size n=2 without replacement and compute the sampling distribution of the mean.
A hospital is studying the delivery time of two different laundry companies. The hospital has been using company a for the past year and is basically satisfied with the time the company takes to return laundry to the hospital. The hospital is prepared to stay with company a if the delivery time is the same or less than that of competitor company, Company B. However, if the hospital finds that the mean delivery time of company b is less than that of company A, it will start using the laundry services of company B. Independent samples show the following delivery time characteristics for both companies:
company A
n1 = 20
mean x1 = 10 days
s1 = 3 days
company b
n2 = 30
mean x2 = 12.5 days
s2 = 2 days
what are the null and alternative hypothesis for this situation?
with an a=.25 what is your conclusion for the hypothesis from part a?
what action do you recommend in terms of which laundry company the hospital should contract?
