6. The number of days of work lost per quarter due to illness by employees at Gale engineering is shown in the table. Year Quarter Days 1 220 2001 2 244 3 160 4 120 1 228 2002 2 240 3 180 4 120 1 232 2003 2 244 3 216 4 124 A time-series has been draw to show the data. The six of the 4-point moving averages have been plotted. (a) Why should the company consider 4-point moving averages? (1) (b) Calculate the remaining 4-point moving averages and plot them on the graph. (3) (c) On your diagram, draw a trend line for the moving averages. (1) The mean seasonal effect for the first quarter is +38. (d) Estimate the number of days of work likely to be lost in the quarter of 2004. (2) The trend is for the number of days of work lost to increase. (e) Suggest a reason for this. (1) 7. The table shows information about the quarterly gas bill, in £’s, for Samira’s house, over a period of two years. Quarter Year 1 2 3 4 1 £200 £162 £80 £130 2 £216 £166 £96 £142 The data has been plotted as a time series (a) The first three 4-point moving averages are £143, £147 and £148. (i) Work out the last two 4-point moving averages. (ii) Plot all five of the moving averages on the graph. (4) (b) What do the moving averages show about the trend of the quarterly gas bills? (1)
6. The number of days of work lost per quarter due to illness by employees at Gale engineering is shown in the table. Year Quarter Days 1 220 2001 2 244 3 160 4 120 1 228 2002 2 240 3 180 4 120 1 232 2003 2 244 3 216 4 124 A time-series has been draw to show the data. The six of the 4-point moving averages have been plotted. (a) Why should the company consider 4-point moving averages? (1) (b) Calculate the remaining 4-point moving averages and plot them on the graph. (3) (c) On your diagram, draw a trend line for the moving averages. (1) The mean seasonal effect for the first quarter is +38. (d) Estimate the number of days of work likely to be lost in the quarter of 2004. (2) The trend is for the number of days of work lost to increase. (e) Suggest a reason for this. (1) 7. The table shows information about the quarterly gas bill, in £’s, for Samira’s house, over a period of two years. Quarter Year 1 2 3 4 1 £200 £162 £80 £130 2 £216 £166 £96 £142 The data has been plotted as a time series (a) The first three 4-point moving averages are £143, £147 and £148. (i) Work out the last two 4-point moving averages. (ii) Plot all five of the moving averages on the graph. (4) (b) What do the moving averages show about the trend of the quarterly gas bills? (1)