S.D/Variance
The variance is found by dividing by n.
False. (N-1)
Find the Mean of these numbers: 46, 67, 89, 23, 12
47.4
Find the Min and Max= 14, 11, 8, 1, 23, 20, 17, 5, 19, 10, 12, 22
Min= 1
Max= 23
Find the IQR: 1, 3, 6, 9, 10, 15, 23
IQR= 12
The point Z with 70% of the observations falling below it.
.52
To find the standard deviation/variance of a set of values:
1. Find the mean of the data.
2. Find the difference (deviation) between each of the scores and the mean
3. Square each deviation.
4. Sum the squares.
5. Dividing by one less than the number of values; Find the “mean” of this sum (the variance).
6. Find the square root of the variance (the standard deviation).
TRUE.
Find the Mean: 12, 13, 14, 15, 16, 17, 147
33.4285
Find the Q1: 21, 4, 18, 9, 25, 16, 27, 30, 33, 15, 31
Q1=15
Find the IQR: 14, 11, 8, 1, 23, 20, 17, 5, 19, 10, 12, 22
IQR=10.5
The point Z with 47% of the observations falling above it.
.08
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
Find the Median: 1, 9, 5, 10, 5, 3, 7
5
Find the Q1: 72, 60, 64, 75, 79, 63, 70, 61, 78
Q1= 62
Find the IQR and (1.5 * IQR): 0,2,4,6,8,10,12
IQR= 8
1.5 * IQR = 12
Z < 2.19
-3.31 < Z
-3.31 < Z < 2.19
.9857
.9995
.9812
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
Find the Mean: 1234, 1570, 784, 36, 9756
2676
Find the Q3: 107, 92, 111, 119, 99, 100, 89, 94, 125, 93
Q3= 111
Find the IQR and Outlier for 7,9, 15, 21, 23,25,29
IQR= 16
1.5 * IQR= 24
Q1(-)= -15
Q3(+)= 49
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.
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
Find the Median: 134, 47, 122, 113, 49, 56, 102, 93, 62
93
Find the 5 Number Summary: 21, 4, 18, 9, 25, 16, 27, 30, 33, 15, 31
Min= 4
Q1= 15
M= 21
Q3= 30
Max= 33
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