In: Statistics and Probability
1. An average department store sells 350 men's suits per year. The men's suit departments at a particular national chain of stores claim they sell more than the industry average. In 45 of their stores, they sold, on the average, 450 suits per year with a population standard deviation of 50. What is the test value for their claim?
2. The average speed of greyhound dogs is about 18.7 meters per second. A particular greyhound breeder claims that her dogs are faster than the average greyhound. In a sample of 30 of her dogs, they ran, on the average, 19.4 meters per second with a standard deviation of $1.5. At α = 0.05, does the data support her claim?
1. As here claim is that mean is greater than 350
So hypothesis here is vs
As population standard deviation is known we will use z statistics
As P value is
So we reject the null hypothesis, hence we have sufficient evidence to support the claim that mean is greater than 350.
2. Here claim is that mean is greater than 18.7
So hypothesis is vs
As population standard deviation is not known we will use t statistics
P value is TDIST(2.56,29,1)=0.008
As P value is less than alpha=0.05, we reject the null hypothesis
Hence we have sufficient evidence to support the claim that mean is greater than 18.7