A computer retailer sells only TFT and LCD style monitors. According to the graph above, where the x-axis represents the day of the week and the y-axis represents the number of monitors sold, on which day was the ratio of the number of LCD monitors sold to total number of monitors sold the greatest?
(C) The number of LCD sales is the difference between total sales and TFT sales. For each day of the week, we can determine the ratio of the number of LCD monitors sold to the total number of monitors sold:
Monday: (18 – 10)/18 = 4/9
Tuesday: (22 – 12)/22 = 5/11
Wednesday: (24 – 12)/24 = 1/2
Thursday: (26 – 16)/26 = 5/13
Friday: (26 – 14)/26 = 6/13.
The greatest fraction is 1/2, so the ratio on Wednesday is the largest.The correct answer is choice (C).
* let L represent the number of LCD monitors sold
* let T represent the number of TFT monitors sold
Why is the ratio calculated as (L-T)/L? I would expect it to be L/(L+T).