CATEGORY 1:
S.D/Variance and IQR
S.D/Variance and IQR
Find the standard deviation of the average temperatures recorded over a five-day period last winter: 18, 22, 19, 25, 12
23.7; 4.8682
The point Z with 70% of the observations falling below it.
.52
65% confidence interval for μ, the true mean (Using Table A, compute the critical value z*).
Z*= .93
USE TABLE C: Data follow a normal distribution with a sample standard deviation s= 20 pounds (lbs). Take a simple random sample (SRS) of size 25. The sample mean is xbar= 365. Calculate the standard error of the mean.
S/S.R of N= 4
For a significance test with Ho: μ=100 and withHa: μ < 100, what is the P-VALUE for the z-statisitic(i.ez-score) z=-2.12?
P= .0170
Find the IQR and (1.5 * IQR): 0,2,4,6,8,10,12
IQR= 8
1.5 * IQR = 12
The point Z with 47% of the observations falling above it.
.08
USE TABLE A: Data follow's a normal distribution with known standard deviation= 0.63 pounds (lbs). Take a simple random sample (SRS) of size 40. The sample mean is x-bar= 1.35. Compute the margin of error for a 95% confidence interval μ.
M.O.E= +/- 0.19523
USE TABLE C: Data follow a normal distribution with known sample standard deviations s=80 pounds (lbs). Take a simple random sample (SRS) of size 16. The sample mean is xbar=500. Calculate the standard error of the mean.
S/ S.R of N= 20
For a significance test with Ho: μ=100 and with Ha:μ does not equal 100, what is the P-VALUE for the z-statistic (i.ez-score) z= - 3.11 ?
P = .0018
Find the variance and standard deviation of the heights of five tallest skyscrapers in the United States: Sears Tower (Willis Building): 1450 feet Empire State Building: 1250 feet One World Trade Center: 1776 feet T Tower: 1388 feet 2 World Trade Center: 1340 feet
40,449.2; 201.1198
Z < 2.19
-3.31 < Z
-3.31 < Z < 2.19
.9857
.9995
.9812
USE TABLE A: Data follow a normal distribution with known sample standard deviation σ= 25 pounds (lbs). Take a simple random sample (SRS) of size 100. The sample mean is x-bar= 365. Compute the margin of error for a 91% confidence interval for μ.
M.O.E= +/- 4.25
USE TABLE C: Let's say you're still browsing apartments and want to construct your own 95% confidence interval. You randomly sample twenty apartment listings and determine that the average monthly rent is $1,000. Assuming a standard deviation of $250. Compute the margin of error for a 95% confidence interval.
M.O.E= +/- 117. 0022
For a significance test with Ho: µ=100 and with Ha: µ ≠ 100, what is the P-VALUE for the z-statistic (i.e z-score) z=1.96
P= .0500
Find the variance and standard deviation of the highest temperatures recorded in eight specific states: 112, 100, 127, 120, 134, 118, 105, and 110.
127.6428; 11.2979
One year, many college-bound high school seniors in the U.S. took the Scholastic Aptitude Test (SAT). For the verbal portion of this test, the mean was 425 and the standard deviation was 110. Based on this information what percentage of students would be expected to score between 350 and 550?
Z scores for 350: -.6818
Z scores for 550: 1.1363
For Z= -.68 proportion= .2483
For Z- 1.13, proportion = .8708.
So, 62.25% of the students would be expected to score between 350 and 550 on their SAT.
USE TABLE A: Assume the population has a normal distribution. A sample of 25 randomly selected students has a mean test score of 81.5 with a standard deviation of 10.2. Compute for a 95% confidence interval
(77.5016, 85.4984)
USE TABLE C: Let's say you're still browsing apartments and want to construct your own 95% confidence interval. You randomly sample twenty apartment listings and determine that the average monthly rent is $1,000. Assuming a standard deviation of $250. Compute for a 95% confidence interval.
(882.9977, 1117.0022)
1.You are not testing Ho: µ=200 against Ha: µ≠ 200 based on your SRS of 25 observations with x ̅= 187 and s=20.
a). What is the correct number of degrees of freedom for this test?
b). Calculate the one-sample t statistic for this test.
a) DF= (N-1) --> 25- 1 = 24
b) T* -3.25
IQR/Outliers?: 21, 4, 18, 9, 25, 16, 27, 30, 33, 15, 31
IQR= 15
1.5 * IQR= 22.9
Q1(-)= -7.9
Q3(+)= 52.9
On an exam, the scores are normally distributed with a mean= 65 and a standard deviation=10.
a)What proportion of students taking a exam will have scores of 47 or higher?
b)Students taking a exam score at least how high in order to be in the highest range with top 12% of all exam scores?
A) .9641
B) 76.75
USE TABLE A: A local bank needs information concerning the savings account balances of its customers. A random sample of 15 accounts was checked. The mean balance was $686.75 with a standard deviation of $256.20. Compute for a 98% confidence interval
(557.0949, 816.4050)
USE TABLE C: Data follow a normal distribution with known sample standard deviations s=80 pounds (lbs). Take a simple random sample (SRS) of size 16. The sample mean is xbar=500. Calculate the standard error of the mean. Compute for a 99% confidence interval
(441.06, 558.94)
1.You are not testing Ho: µ=200 against Ha: µ≠ 200 based on your SRS of 16 observations with x ̅= 215 and s=24.
a). What is the correct number of degrees of freedom for this test?
b). Calculate the one-sample t statistic for this test.
c) What two critical values T* from TABLE C bracket the value of T you get in part (b)?
d) What two P-Value bracket the P-Value from T* you get in part (b)?
a) DF= (N-1) --> 16- 1 = 15
b) T*= 2.5
c) 2.249 < T* < 2.602
d) .04 > P > .02