Derive a general expression for the average failure rate of a Weibull distribution between two point in time, t1 and t2.
In: Statistics and Probability
Question 1
A camera is located 3km away from the entrance gate of a port to count the number of incoming trucks. Trucks that have passed the camera but have not passed the gate are considered to be in the queueing system, in which some trucks are waiting to be serviced by the gate and the other trucks are being serviced by the gate. If truck A passes the camera before truck B, it will pass the gate no later than truck B (first-come-first serve). If truck A passes the camera later than truck B, it will pass the gate no earlier than truck B. Suppose the port does not work at mid-night, and the gate opens at 7:00am. The cumulative numbers of trucks that have passed the camera and the gate at different times of a day are shown in the table below. For brevity, assume trucks pass the camera and the gate only at 6:00, 6:10, 6:20, etc. That is, suppose that in the table below 5 trucks passed the camera exactly at 6:10, and 10 trucks pass the gate exactly at 7:10.
Table Q1-1. Cumulative numbers of trucks that have passed the camera and the gate
Time |
6:00 |
6:10 |
6:20 |
6:30 |
6:40 |
6:50 |
#camera |
0 |
5 |
10 |
25 |
44 |
50 |
#gate |
0 |
0 |
0 |
0 |
0 |
0 |
Time |
7:00 |
7:10 |
7:20 |
7:30 |
7:40 |
7:50 |
#camera |
60 |
62 |
81 |
88 |
95 |
105 |
#gate |
0 |
10 |
20 |
35 |
55 |
75 |
Time |
8:00 |
8:10 |
8:20 |
8:30 |
8:40 |
8:50 |
#camera |
110 |
112 |
115 |
130 |
132 |
139 |
#gate |
95 |
110 |
111 |
115 |
125 |
139 |
Q1.1: Calculate the average flow rate per hour of the system for the three hours from 6:00am to 8:59:59am.
Q1.2: (You can use software tools, e.g., Microsoft Excel, to help answer this question.) Calculate the average flow time of all flow units.
Q1.3: (You can use software tools, e.g., Microsoft Excel, to help answer this question.) Calculate the average inventory of the system from 6:00am to 8:59:59am, that is, the average number of trucks in the system at 6:00:01, 6:10:01, 6:20:01, 6:30:01, 6:40:01, … 8:40:01, 8:50:01.
In: Statistics and Probability
The following table shows the beta carotene and chlorophyll contents of curry (spice) leaves under different postharvest treatments.
Postharvest storage temperature & treatment |
β-carotene (µg/g) |
Chlorophyll (mg/g) |
Fresh |
500 ± 1.5 |
22.8 ± 1.2 |
Oven-dried (60 oC) |
148 ± 1.2 |
9.9 ± 1.2 |
Air-dried (25 oC) |
357 ± 1.3 |
15.9 ± 1.1 |
Frozen (-15 oC) |
398 ± 1.5 |
20.9 ± 1.1 |
Were there significant differences in carotene and chlorophyll contents under the different postharvest treatments?
In: Statistics and Probability
Authors in the New England Journal of Medicine investigated a possible link between Zika virus and microcephaly (or other fetus developmental abnormalities) and researchers collected the following data from Rio de Janeiro state in Brazil (data from March 2016):
Baby with microcephaly |
Baby without microcephaly |
Row totals |
|
Pregnant mum with Zika |
12 |
30 |
42 |
Pregnant mum w/o Zika |
0 |
16 |
16 |
Column totals: |
12 |
46 |
58 |
Test for independence between maternal Zika virus infection and a baby’s microcephaly. Report here the test you are using, the p-value you get, and the conclusion you come to
In: Statistics and Probability
The following table shows the beta carotene and chlorophyll contents of curry (spice)
leaves under different postharvest treatments.
Postharvest storage temperature & treatment |
β-carotene (µg/g) |
Chlorophyll (mg/g) |
Fresh |
500 ± 1.5 |
22.8 ± 1.2 |
Oven-dried (60 oC) |
148 ± 1.2 |
9.9 ± 1.2 |
Air-dried (25 oC) |
357 ± 1.3 |
15.9 ± 1.1 |
Frozen (-15 oC) |
398 ± 1.5 |
20.9 ± 1.1 |
Were there significant differences in carotene and chlorophyll contents under the
different post harvest treatments?
In: Statistics and Probability
Three machines M1, M2 and M3 produce nominally identical items. The evidence of the engineers past experience is that 5 % of the output from machine M1 is faulty, 3.5 % of the output from machine M2 is faulty and 2.5 % of the output from machine M3 is faulty. On a given day, M1 has produced 15 % of the total output, M2 has produced 30 % and M3 the remainder.
An item selected at random is found to be faulty.
In: Statistics and Probability
A researcher believes that there is a positive relationship between the time spent in studying and the score a student gets at the end of the semester. She selected a sample of students and recorded the following data:
Time Spent in minutes |
Score out of 100 |
120 |
86 |
75 |
83 |
60 |
78 |
45 |
75 |
180 |
91 |
30 |
72 |
90 |
84 |
After analyzing the data using Microsoft Excel, the researcher got the outputs below:
Answer the following (Please, use at least 2 decimals when you type numbers ):
a. The correlation coefficient (r) = Answer
b. The relationship between the time spent in studying and the score a student gets is: Answerweak and positivestrong and negativeweak and negativestrong and positive
c. The y-intercept equals: Answer
d. The regression (time spent) coefficient equals = Answer
e. The regression model will be: AnswerScore = 70.704 + 0.123 MinuteMinute = 0.123 + 70.704 ScoreScore = 0.123 + 70.704 MinuteMinute = 70.704 + 0.123 Score
f. From the regression model, the researcher can predict that if a student spends 2.5 hours, the score he gets will be: Answer
g. From the regression model, if a student did not study at all, his score would be expected to be: Answer
h. The coefficient of determination for this model is: Answer95708890%
In: Statistics and Probability
Consider the following Markov chain:
0 |
1 |
2 |
3 |
|
0 |
0.3 |
0.5 |
0 |
0.2 |
1 |
0.5 |
0.2 |
0.2 |
0.1 |
2 |
0.2 |
0.3 |
0.4 |
0.1 |
3 |
0.1 |
0.2 |
0.4 |
0.3 |
In: Statistics and Probability
Calculate the 95% prediction intervals for the four different investments included in the following table. Small Stocks S&P 500 Corporate Bonds T-Bills Average Return 18.37% 11.84% 6.47% 3.46% Standard Deviation of returns 38.79% 20.01% 6.98% 3.14% A.The 95% prediction interval of small stocks is between ?% and ?%. (Round to two decimal places and put the lower number first.) B. The 95% prediction interval of the S&P500 is between ?% and ?%.(Round to two decimal places and put the lower number first.) C. The 95% prediction interval of corporate bonds is between ?% and ?%. (Round to two decimal places and put the lower number first.) D. The 95% prediction interval of T-bills is between ?% and ?% (Round to two decimal places and put the lower number first.)
In: Statistics and Probability
A producer of soap dispensers claims its machine dispense liquid with a standard deviation of 3.1 ounces. A random sample of 20 machines found the standard deviation to be 4.6 ounces. Is there enough evidence, at the α = 0.05 level of significance, to suggest the standard deviation is not 3.1 ounces?
A manufacturer of 10cm marbles claims the standard deviation of it’s marble's diameter is less than 0.21cm. A random sample of 12 marbles found the standard deviation of the diameter to be 0.14cm. Is there enough evidence, at the α = 0.01 level of significance, to back up the manufacturers claim?
A powerpack is manufactured with a mean lifetime of 4 years and a standard deviation of 0.6 years. What percent of the powerpacks will have a lifetime greater than 4.1 years?
If a company makes LED lights with a mean lifetime of 2000 hours and a standard deviation of 120 hours. What percent of the lights have a lifetime between 1840 and 2100 hours?
In: Statistics and Probability
Discrete Math: 7) How many 4-element DNA sequences..
a) Do not contain the base T?
b) Contain the sequence ACG?
c) Contain all four bases A, T, C, and G?
d) Contain exactly three of the four bases?
In: Statistics and Probability
Please show all work
A bottling company uses a filling machine to fill plastic bottles with a popular cola. The bottles are supposed to contain 300 milliliters (ml). In fact, the contents vary according to a normal distribution with mean µ=303 ml and standard deviation σ= 3 ml
What is the probability that an individual bottle contains less than 300 ml?
What is the probability that the sample mean of 80 bottles is less than 300 ml?
In: Statistics and Probability
The results indicated no difference between the means when the statstics-only condition was compared to the combined statistics+victim condition. Compute the tLSD value here.
donations differed significantly by request type, F(2, 55) = 3.35, p < .05,
η2 = .109, MSE. 2.98. In planned comparisons based on Small et al.’s
findings (2007, Study 3), donations were higher when a personalized victim
appeared alone (M = $3.18, n =17) than when statistics were added to the
victim request (M = $2.00, n = 22, p = .04) or when statistics were presented
alone (M = $1.79, n = 19, p = .02). The latter two means did not differ.
In: Statistics and Probability
Five hundred consumers were surveyed about a new brand of snack
food, Crunchicles. Their age groups and preferences are
given in the table.
18–24 | 25–34 | 35–55 | 55 and over | Total | |
---|---|---|---|---|---|
Liked Crunchicles | 4 | 20 | 23 | 35 | 82 |
Disliked Crunchicles | 47 | 56 | 44 | 38 | 185 |
No Preference | 27 | 8 | 28 | 170 | 233 |
Total | 78 | 84 | 95 | 243 | 500 |
One consumer from the survey is selected at random. Use
reduced fractions for your responses to each of
the following questions.
What is the probability that the consumer is 18–24 years of age,
given that he/she dislikes Crunchicles?
What is the probability that the selected consumer dislikes
Crunchicles?
What is the probability that the selected consumer is 35–55 years
old or likes Crunchicles?
If the selected consumer is 70 years old, what is the probability
that he/she likes Crunchicles?
In: Statistics and Probability
what are the strength and weaknesses of formal theory
and statistical analysis? how can these methods be combined with
qualitative methods?
(word limit:700 words)
In: Statistics and Probability