# Help with Homework

#### Jobless Jack

##### New Member
Hi these are practice questions from our class.

can someone please help me by cheaking if i have done the correct answear ? if i am wrong could someone please provide the correct answear ? Thanks

1. The z-value that is used to construct a 95% confidence interval is
A 1.28 B 1.96
C 2.58 D 1.64

Ans: B

2. For a symmetric distribution
A. the mean is larger than the median.
B. the mean, median and the mode are equal.
C. the mean is smaller than the median.
D. the mode is the largest value.

Ans:B
3. Which graph can describe the frequency distribution of categorical variable？
A bar chart B pie chart
C histogram D scatter graph

Ans: A

4. In the chi-square test of 2×2 table, When should we choose the Yate’s correction formula?
A. n≥40 and 1≤O＜5 B. 1≤O＜5
C. 1≤E＜5 D. n≥40 and 1≤E＜5

Ans: D

5. In order to investigate the status of the patients with hypertension. The results show that there are 50 patients and 50 healthy people in 100 residents. Such kind of data is
A. numerical data B. multichotomus data
C. binary data D. ordinal data.

Ans: A

6. In the comparison of two-independent samples mean, df is
A n1-1 B n2-1
C n1+ n2-1 D n1+ n2-2

Ans A

7 The standard normal distribution
A is a special case of the normal distribution.
B. has a mean of 0 and a standard deviation of 1.
C. measures the distance from the mean in units of the standard deviation.
D all of the above.
Ans D

8 In the paired t-test, we assume in the null hypothesis that the distribution of the differences between the paired observation has a mean
A. equal to 1. B. equal to n - 1.
C.equal to 0. D. none of the above
ANs

9 In a random sampling (n = 400), we got a sample with the mean of 60 and the standard deviation of 10, then the standard error of the sample mean will be
A 0.5 B 30 C 0.025 D 0.15

ANs : D

10 The standard error of the mean
A is less than the standard deviation
B decreases as the sample size increases while standard deviation in definite.
C measures the variability of the mean from sample to sample
D all of the above

11 If we wish to determine whether there is evidence that the proportion of successes is higher in group 1 than in group 2 and we have obtained independent samples from the two groups, the appropriate test to use is
A t test B chi-square test
C F test D rank sum test
Ans : F test

12. When sample size increases,
A. standard error increases B. standard deviation increases
C. standard deviation decreases D. standard error decreases
Ans : C

13. Wilcoxon rank sum test was used to analyze the difference of the following two groups, the observations in the experimental group are 0, 0, 7, 14, 32, 40, while the observations in the control group are 0, 1, 2, 4, 4, 8. The “0”in the above groups should be ranked as

A. 2, 3, 1 B. 1.5, 1.5, 3
C. 2, 2, 2 D. 2.5, 2.5, 1
Ans D