|x: cars/5 min|
The data is the number of cars per five minute period passing past Song Mahs, Pehleng, Kitti over the course of an hour from 17:08 to 18:08 on Monday evening, 30 October 2006.
Presume that the number of cars per five minute period distribution data comes from a normal distribution. The following problems derive from chapter seven. Use the standard normal distribution to determine your answers. Use the sample mean x from question one for µ, and the sample standard deviation sx from question two for σ in the questions below. Use a spreadsheet to calculate z values and probabilities as appropriate. Here the variable is x and NOT x.
Use the sample mean x from question one and the sample standard deviation sx from question two and the data given in the first table to calculate a 95% confidence interval for the population mean µ number of cars per five minute periods using the student's t-distribution.
|Statistic or Parameter||Symbol||Equations||Excel|
|Chapter seven: Normal statistics|
|Calculate a z value from an x||z||=||=STANDARDIZE(x; µ;σ)|
|Calculate an x value from a z||x||= z σ + µ||=z*σ+µ|
|Find a probability p from a z value||=NORMSDIST(z)|
|Find a z value from a probability p||=NORMSINV(p)||Chapter eight: Distribution of the sample mean x|
|Calculate a z-statistic from an x||z||=(x - µ)/(sx/SQRT(n))|
|Calculate a t-statistic (t-stat)||t||=(x - µ)/(sx/SQRT(n))|
|Calculate an x from a z||=µ + zc*sx/sqrt(n)|
|Chapter nine: Confidence interval statistics|
|Degrees of freedom||df||= n-1||=COUNT(data)-1|
|Find a tc value from a confidence level c and sample size n||tc||=TINV(1-c;n-1)|
|Calculate an error tolerance E of a mean for any n ≥ 5 using sx.||E||=tc*sx/SQRT(n)|
|Calculate a confidence interval for a population mean µ from the sample mean x and error tolerance E:||x-E ≤ µ ≤ x+E|
Calendar • Statistics • Lee Ling • COMFSM