Date | May 2022 | Marks available | 4 | Reference code | 22M.2.SL.TZ2.5 |
Level | Standard Level | Paper | Paper 2 | Time zone | Time zone 2 |
Command term | Hence and Find | Question number | 5 | Adapted from | N/A |
Question
A cafe makes litres of coffee each morning. The cafe’s profit each morning, , measured in dollars, is modelled by the following equation
where is a positive constant.
The cafe’s manager knows that the cafe makes a profit of when litres of coffee are made in a morning.
The manager of the cafe wishes to serve as many customers as possible.
Find an expression for in terms of and .
Hence find the maximum value of in terms of . Give your answer in the form , where is a constant.
Find the value of .
Use the model to find how much coffee the cafe should make each morning to maximize its profit.
Sketch the graph of against , labelling the maximum point and the -intercepts with their coordinates.
Determine the maximum amount of coffee the cafe can make that will not result in a loss of money for the morning.
Markscheme
attempt to expand given expression (M1)
M1A1
Note: Award M1 for power rule correctly applied to at least one term and A1 for correct answer.
[3 marks]
equating their to zero (M1)
(A1)
substituting their back into given expression (M1)
A1
[4 marks]
substituting into given expression and equating to M1
A1
[2 marks]
A1
[1 mark]
A1A1A1
Note: Award A1 for graph drawn for positive indicating an increasing and then decreasing function, A1 for maximum labelled and A1 for graph passing through the origin and , marked on the -axis or whose coordinates are given.
[3 marks]
setting their expression for to zero OR choosing correct -intercept on their graph of (M1)
litres A1
[2 marks]