http://imgur.com/a/P0CCe
Hi, for question 321 B wht do i draw 2x on tthe graph
And how do i do ei and ii
Hi, sorry this reply is so late. I don't do further but I'll see if I can help
So for 321.b), the number of dogs clipped is at least 2* number of dogs washed
So y ≥ 2*x
You'd have to draw the line y=2x and since it's a greater than or equal sign, it'd be the area above this line.
Profit = 40x + 30y
e)(i) I'm not sure if they expect you to work it out mathematically as it's only worth 1 mark per part. Profit from one dog washed is more than a clipped dog. This means one x is worth more than one y. Also, x and y have to be whole numbers. So, I believe you could either use the graph or guess-and-check. As washing a dog is both faster and gives more money, you want the largest x value. Using the graph (from VCAA answers) the largest x value within the bounds is 2, and for an x value of 2 the largest y value is 6.
Alternatively, you can start with the maximum number of dogs clipped which is 8, and decrease number of clips by one and increase number of washes by one (they take similar time to complete, so doing this just a few times is easy). 2 washes and 6 clips is the highest number of washes possible, and 6 clips is the highest number of clips with 2 washes. (clips ≥ 2*washes)
This question's more interpreting from the graph rather than solving it.
e)(ii) Just sub in these values.
Sorry my answer's not more concise (and a bit late) but hope this helps anyway