Neco 2018 Data Processing Question 50

A spreadsheet records the monthly sales (in thousands of units) of three products over six months as follows:\n\\[\n\begin{array}{c|ccc}\n\text{Month} & X & Y & Z \\ \hline\nJan & 120 & 80 & 200 \\nFeb & 135 & 88 & 190 \\nMar & 150 & 96 & 185 \\nApr & 165 & 104 & 175 \\nMay & 180 & 112 & 170 \\nJun & 195 & 120 & 160 \ \end{array}\n\\]\n\n(a) Compute the total sales for each product over the six months.\n(b) For each product, find the average monthly percentage growth (use the five month‑to‑month changes).\n(c) Using the total monthly sales (sum of the three products for each month), determine the linear regression equation \(y = mx + c\) where \(x\) is the month number (Jan = 1) and \(y\) is the total sales. Then forecast the total sales for July (\(x = 7\)).\n(d) Which type of chart would best display the trend of the total monthly sales over the six months?