Homework help II
Blackroyal
order_36091_HomeworkHelpII1.docx4). The following frequency distribution table lists the time (in minutes) that participants were late for an experimental session. Compute the sample mean, median, and mode for these data.
|
mean |
1 min |
|
median |
2 min |
|
mode |
3 min |
|
Time (min) |
Frequency |
|
0 |
2 |
|
2 |
5 |
|
4 |
2 |
|
7 |
1 |
|
9 |
3 |
7). A neuroscientist measures the reaction times (in seconds) during an experimental session in a sample of cocaine-addicted
(n = 8),
morphine-addicted
(n = 12),
and heroin-addicted rats
(n = 6).
Mean reaction times in each sample were 11, 17, and 14 seconds, respectively. What is the weighted mean for all three samples? Hint: The overall mean is not 14.0 seconds. (Round your answer to two decimal places.) 1 sec
9). A group of researchers measure the weight of five participants prior to a clinical weight loss intervention. They record the following weights (in pounds): 200, 250, 300, 100, and 150 pounds. The mean is 200 pounds. Using the original example of five weights, the researchers added a sixth participant to the sample.
(a) If the sixth participant weighed 240 pounds, will the mean increase, decrease, or not change?
The mean will increase. The mean will decrease. The mean will not change.
(b) If the sixth participant weighed 200 pounds, will the mean increase, decrease, or not change?
The mean will increase. The mean will decrease. The mean will not change.
(c) If the sixth participant weighted 160 pounds, will the mean increase, decrease, or not change?
The mean will increase. The mean will decrease. The mean will not change.
10). Gilman and colleagues (2008) measured general life satisfaction in 1,338 adolescents from two individualistic nations (Ireland, United States) and two collectivist nations (China, South Korea) using the Multidimensional Students' Life Satisfaction Scale (MSLSS). Mean participant scores on the MSLSS are given in the following table.
|
Nation |
Gender |
|
|
|
Men |
Women |
|
United States |
4.39 |
4.61 |
|
Ireland |
4.37 |
4.64 |
|
China |
4.41 |
4.56 |
|
South Korea |
3.92 |
3.78 |
|
|
|
|
(a) Among which group was general life satisfaction lowest on average?
women from Ireland women from the United States women from China men from South Korea men from the United States men from China Women from South Korea men from Ireland
(b) Among which group was general life satisfaction highest on average?
men from the United States men from Ireland women from South Korea women from Ireland women from China men from China men from South Korea women from the United States
12). Based on the empirical rule, what percentage of data fall within 1 SD, 2 SD, and 3 SD of the mean for data that are distributed normally? (Enter your answers to one decimal place.)
|
1 % of all scores lie within 1 SD of the mean |
|
2 % of all scores lie within 2 SD of the mean |
|
3 % of all scores lie within 3 SD of the mean |
13) A social scientist measures the number of minutes (per day) that a small hypothetical population of college students spends online.
|
Student |
Score |
Student |
Score |
|
A |
73 |
F |
89 |
|
B |
94 |
G |
98 |
|
C |
39 |
H |
82 |
|
D |
98 |
I |
89 |
|
E |
53 |
J |
99 |
For each calculation, note that there are 10 scores in which the highest score is 99 and the lowest score is 39.
14).A sociologist records the annual household income (in thousands of dollars) among a sample of families living in a high-crime neighborhood. Locate the lower, median, and upper quartiles for the times listed below. Hint: First arrange the data in numerical order.
|
lower quartile |
|
1 thousand dollars |
|
median |
|
2 thousand dollars |
|
upper quartile |
|
3 thousand dollars |
|
35 |
38 |
|
41 |
47 |
|
23 |
38 |
|
55 |
46 |
|
31 |
22 |
|
38 |
42 |
|
21 |
31 |
|
45 |
38 |
|
20 |
52 |
|
35 |
47 |
|
|
|
|
Q1 |
28.5 |
|
MEDIAN |
38 |
|
Q3 |
45.5 |
Arrange the data in numeric order before finding the quartiles.
15) A psychopathologist records the number of criminal offenses among teenage drug users in a nationwide sample of 1,601 participants. To measure the variance of criminal offenses, he computes SS = 25,600 for this sample.
(a) What are the degrees of freedom for variance? 1 (b) Compute the variance and standard deviation.
|
variance |
2 |
|
standard deviation |
3 |
Given SS, you only need to determine the degrees of freedom for variance to calculate the sample variance.
16). State whether each of the following will increase, decrease, or have no effect on the population variance.
(a) the sum of squares (SS) increases
This change will increase the population variance. This change will decrease the population variance. This change will have no effect on the population variance.
(b) the sample size decreases
This change will increase the population variance. This change will decrease the population variance. This change will have no effect on the population variance.
(c) the size of the population increases
This change will increase the population variance. This change will decrease the population variance. This change will have no effect on the population variance.
Note that only values used to compute the population variance can change the value of this measure.
17). A researcher measures the time (in seconds) it takes a sample of five participants to complete a memory task. It took four of the participants 5, 6, 6, and 7 seconds. If
M = 6,
then what must be the fifth time recorded? 1 sec
18). An expert reviews a sample of 10 scientific articles
(n = 10)
and records the following number of errors in each article: 8, 6, 3, 5, 8, 2, 1, 5, 9, and 4. Compute SS, variance, and standard deviation for this sample using the definitional and computational formula. (Round your answers to two decimal places.)
|
SS |
|
1 |
|
variance |
|
2 |
|
standard deviation |
|
3 errors |
The definitional formula is given in Section 4.5; the computational formula is given in Section 4.7.
19). A professor records the time (in minutes) that it takes 16 students to complete an exam. Compute the SS, the variance, and the standard deviation assuming the 16 students constitute a population and assuming the 16 students constitute a sample. (Round your answers for variance and standard deviation to two decimal places.)
|
45 |
46 |
41 |
20 |
|
43 |
23 |
52 |
50 |
|
35 |
38 |
31 |
35 |
|
40 |
42 |
25 |
22 |
(a) the 16 students constitute a population
|
SS |
|
1 |
|
variance |
|
2 |
|
standard deviation |
|
3 min |
(b) the 16 students constitute a sample
|
SS |
|
4 |
|
variance |
|
5 |
|
standard deviation |
|
6 min |
Note that only the denominator of the variance formula is different for samples and populations.
20). To study bonding between mothers and infants, a researcher places each mother and her infant in a playroom and has the mother leave for 10 minutes. The researcher records crying time in the sample of infants during this time that the mother was not present and finds that crying time is normally distributed with
M = 6
and
SD = 1.2.
Based on the empirical rule, state the range of crying times within 68% of infants cried, 95% of infants cried, and 99.7% of infants cried.
(a) 68% of infants cried 1 to 2 min (b) 95% of infants cried 3 to 4 min (c) 99.7% of infants cried 5 to 6 min
Make sure you identify the cutoff values at the first, second, and third standard deviations.
19.6
RN_3119349_13
2
RN_3119349_13
1400
RN_3119420_14
36
6
RN_3119300_3_
RC_3119447_15_
RN_3119321_16
65.5
RN_3119388_17
6.55
RN_3119388_17
2.5593
2
22396
RN_3119316_18
121.68
RN_3119316_18
11.031
1947
RN_3119316_18
129.8
6.6
RN_3119291_19
9.4
RN_3119291_19
5.2
10.8
3.8
RN_3119291_19
12.2
RN_3119411_6_
mc
RC_3119385_8_0
{}
RC_3119385_8_1
4
RC_3119333_9_0
68
RN_3119300_3_
RN_3119430_11
95
RN_3119430_11
99.7
60
RN_3119404_12
22
{"js_version":0}
11
384.16
RN_3119404_12
