QMB 3200 ALL YOU NEED; GOOD
EXAM QUESTIONS WITH THEIR
ANSWERS FOR REVISION
Find z the area to the left of Z
ex: z = .2119
use row and column
area = -.80
Find z area between z values
ex: area between -z and z is .9030
divide z by 2 then add .5. Then use z table to find area.
.9030/2=.4515+.5=.9515
.9515 in z table is z=1.66
Find z area right of z
ex: area right of z is .06915
subtract area from 1 and go to z table to find z
1-.06915 = .3085
z = -.50
Mean
= sum of x/n
population mean
μ =. sum of x/n
,median
value in middle
mode
value occurs most
Weighted Mean Formula
x bar = ∑ (w • x) / ∑w
geometric mean
sum of x to the root of n
percentiles
Divide the data set into 100 equal parts. An observation at the
Pth percentile is higher tha P percent of all observations.
= p/100 (n+1)
statistics
Collection of methods for planning experiments, obtaining data,
organizing, summarizing, presenting, analyzing, interpreting,
and drawing conclusions based on data.
sample
a subset of the population
Population
the set of all elements of interest in a particular study
quartiles
,min, q1, q2, q3, q4, max
q1
median of lower half
q3
median of upper half
q2
median
q4
3/4
variance
The average of the squared differences from the mean. in excel
= VAR.S
variance sample data
s² = ∑(xi - x̅)² / n-1
variance population
σ² = ∑(xi - μ )² / n-1
standard deviation sample
s = √s²
standard deviation population
σ = √σ²
, standard dev ex: the variance of a sample of 81 observations is
64. the standard deviation of the sample is what
s = √64 = 8
Variance ex: sample data is 3,5,12,3,2 the mean is 5. what is
the variance
s² = (3-5)² + (5-5)² + (12-5)² + (3-5)² + (2-5)² = 66/(5-1) = 66/4 =
16.5
covariance
sxy =
∑(xi - x̅) (yi - ybar)/n-1
find differences between x and mean then y and mean and
FIRST multiply the differences then add all the products of the
differences to come up with the sum.
covariance ex:
n = 1,2,3,4,5
x = 4,6,11,3,16
x̅ = 8
y = 50,50,40,60,30
y bar = 46
step 1)
(4-8) (50-46) = -4 x 4 = -16
(6-8) (50-46) = -8
(11-8) (40-46) = -18
(3-8) (60-46) = -70
(16-8) (30-46) = -128
EXAM QUESTIONS WITH THEIR
ANSWERS FOR REVISION
Find z the area to the left of Z
ex: z = .2119
use row and column
area = -.80
Find z area between z values
ex: area between -z and z is .9030
divide z by 2 then add .5. Then use z table to find area.
.9030/2=.4515+.5=.9515
.9515 in z table is z=1.66
Find z area right of z
ex: area right of z is .06915
subtract area from 1 and go to z table to find z
1-.06915 = .3085
z = -.50
Mean
= sum of x/n
population mean
μ =. sum of x/n
,median
value in middle
mode
value occurs most
Weighted Mean Formula
x bar = ∑ (w • x) / ∑w
geometric mean
sum of x to the root of n
percentiles
Divide the data set into 100 equal parts. An observation at the
Pth percentile is higher tha P percent of all observations.
= p/100 (n+1)
statistics
Collection of methods for planning experiments, obtaining data,
organizing, summarizing, presenting, analyzing, interpreting,
and drawing conclusions based on data.
sample
a subset of the population
Population
the set of all elements of interest in a particular study
quartiles
,min, q1, q2, q3, q4, max
q1
median of lower half
q3
median of upper half
q2
median
q4
3/4
variance
The average of the squared differences from the mean. in excel
= VAR.S
variance sample data
s² = ∑(xi - x̅)² / n-1
variance population
σ² = ∑(xi - μ )² / n-1
standard deviation sample
s = √s²
standard deviation population
σ = √σ²
, standard dev ex: the variance of a sample of 81 observations is
64. the standard deviation of the sample is what
s = √64 = 8
Variance ex: sample data is 3,5,12,3,2 the mean is 5. what is
the variance
s² = (3-5)² + (5-5)² + (12-5)² + (3-5)² + (2-5)² = 66/(5-1) = 66/4 =
16.5
covariance
sxy =
∑(xi - x̅) (yi - ybar)/n-1
find differences between x and mean then y and mean and
FIRST multiply the differences then add all the products of the
differences to come up with the sum.
covariance ex:
n = 1,2,3,4,5
x = 4,6,11,3,16
x̅ = 8
y = 50,50,40,60,30
y bar = 46
step 1)
(4-8) (50-46) = -4 x 4 = -16
(6-8) (50-46) = -8
(11-8) (40-46) = -18
(3-8) (60-46) = -70
(16-8) (30-46) = -128
