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# As-level -> Maths Pure HELP!! watch

1. Hi,
I need help with just a few modelling type quadratics questions.

1) y = miles per gallon x= speed of car
y=-0.01x2 + 0.975x +16, x > 0

a) Use the model to find two speeds at which the car has a fuel consumption of 32.5 mpg.

b) Rewrite y in the form A-B(x-C)2
- I have B as 0.01 and C as 48.75. However I have 16 for A and the answer booklet says it is 39?? I don't know how to get to that answer.

2) A fertiliser company uses a model to determin how the amount of fertilser used, f kilograms per hectare, affects the grain yeild g, measures in tonnes per hectare.

g= 6 + 0.03f - 0.00006f2

a) One farm currently uses 20 kilograms of fertiliser per hectare. How much more feriliser would he need to use to increase his yeild grain by 1 tonne per hectare?

3) A football stadium has 25 000 seats. The football club knows that they will sell only 10,000 tickets if each ticket costs £30. They also expect to sell 1,000 more tickets every time the price goes down by £1.

a) The number of tickets sold, t, can be modelled by the linear equation
t=M-1000p
where £p is the price of each ticket and M is a constant. Find the value of M.

The total revenue, £r, can be calculated by multiplying the number of tickets sold by the price of ach ticket. This can be written as:

r=p(M-1000p)

b)Rearrange r into the form A-B(p-C)2 where A, B and C are constants to be found.

c) Using your answer to part b or otherwise, work out how much the football club should charge for each ticket if they wanted to make maximum amount of profit.
2. So for question one, you need to find the x values for which y=32.5
3. (Original post by M4cc4n4)
So for question one, you need to find the x values for which y=32.5
Thank you, Ive spotted my mistake on that question now. ahah Any ideas about part 'b' or any other questions??
Thank you again.
4. You forgot to take away the 47.75^2 on b and as it is both - they add and when -0.01 it becomez 39.765625 or something

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