The “cold start ignition time” of an automobile engine is being investigated by a gasoline manufacturer. The following times (in seconds) were obtained for a test vehicle: 1.75, 1.92, 2.62, 2.35, 3.09, 3.15, 2.53, 1.91.
(a) Calculate the sample mean, sample variance, and sample standard deviation.
(b) Construct a box plot of the data.
Step 1 of 2
The following times (in seconds) were obtained for a test vehicle:
We are asked to find the sample mean, sample variance and standard deviation.
If the observations in a sample are denoted by the sample mean is,
Let be the cold start ignition time ( in seconds)
The number of measurements is
The sample variance,
We can rewrite equation (2) as,
[ from the data]
Hence the sample mean, sample standard deviation and sample variance of the cold start ignition time are respectively.