T-Test Statistic Problems
Creative Good, a New York consulting firm, claimed that 39% of shoppers fail in their
attempt to purchase merchandise on-line because Web sites are too complex. A random
sample of 60 on-line shoppers selected and 15 rep
Standard Deviation Problems
If standards deviation is 6 what is the sum of squares?
Standard Deviation = Sqrt( Variance)
Variance we know that = Sum(Xi)^2 [Sum(Xi)]^2/ n
Variance= Sum(x^2)/N- u^2
& we have S.D = Sqrt( Variance)
Pooled Variance Problems
Calculate the Pooled Variance for the following sample data & Test the Hypothesis.
Once using the pooled variance calculated above and the second time using assumption of
unequal variances. If needed, consider the origin
Normal Distribution Problems
If the mean is 60 and the standard deviation is 9 and 79 subjects completed the test.
a) How many sores will fall above 70?
b) Between 56 and 72?
c) Between 50 and 57?
Let X = Scores
a) We want to find P(X >
Normal Distribution Problems
A melting point test of n=10 samples of a binder used in manufacturing a rocket propellant
resulted in average of 154.2 F
Assume that melting point is normally distributed with a standard deviation of 1.5F
Test Ho: U
Margin of Error Problems
A national safety council wishes to estimate the proportion of automobile accidents that
involve pedestrians. How large a random sample of accident records must be examined to be
96% certain that the estimate has a margi
Hypothesis Test Problems
A recent broadast of televison show had a 10 share, meaning that among 6000 monitored
households with TV sets in use 10% of them were tuned to this program. Use a 0.01
significance level to test the claim of an advertise
Distribution Problems Stats
The administration of Whatsamatta University wishes to determine if the mean credit card
debt of its
Students exceed the national average of $2200. A survey of 50 students at Whatsamatta
gave a mean credit card debt
Correlation Co-efficient with t-test Statistic
If n = 15 and r = .4296, the corresponding t-statistic to test for zero correlation is what?
Formula for calculating t-test statistic with correlation is
T = r / Sqrt (1-r^2)/n-2
Confidence Interval Problems-Question)
Suppose that the same firm develops a new light bulb, with the goal of producing a light bulb
with a longer lifetime at the same cost. If 100 of the new bulbs are tested, yielding a sample
mean of 2100 hours and a sa
Confidence Interval Problems
For several years researchers have noticed that there appears to be a regular, year-to-year
Increase in the average IQ for the general population. This phenomenon is called the
Flynn effect after the researcher who f
Confidencce Interval Problems.
A survey shows that a family of 3 spends on average about $3500 on
a vacation. The survey was conducted on 200 families. Assuming a
standard deviation of $450, find the 95% condence interval of the
Calculate the unknowns for the following situations based on the given data.
Actual total sales revenue $400,000
Total fixed cost $75,000
Unit variable cost $15
Contribution margin ratio 40%
a) Breakeven point in dollars
b) unit s