The production line data of battery life (in months) produced by a company are given below:

<img src='./qimages/10346-1a.jpg'>

Which control charts should be used to control the process mean and process variability?

Construct these charts and check whether the process is under statistical control or not.

Also plot the revised control charts, if necessary.

The following table gives the results of daily inspection of vacuum tubes for 26 days of a month:

<img src='./qimages/10346-1b.jpg'>

Draw a suitable control chart and interpret the result.

Also plot the revised control chart, if necessary.

2. The following data on monthly sales (in Rs monthly advertisement cost (in Rs'000s) and price per litre of juice (in Rs) were obtained for 20 months to explore the relationship of sales with advertisement cost and price of juice:

<img src='./qimages/10346-2.jpg'>

Prepare a scatter matrix plot to get an idea about the relationship among the variables.

Develop a regression model and perform its analysis at level of significance.

Check linearity and normality assumptions for the fitted regression model.

3. The data for the number of persons visiting a place of interest from 2013 to 2015 are given in the following table

<img src='./qimages/10346-3.jpg'>

Compute the seasonal indices using Ratio-to-trend method.

Obtain the deseasonalised values.

Plot given data and the deseasonalised values.