Production problem

[computer-bot]

A product's production cost is x for the first 1000 units and y for every subsequent unit. If z is greater than 1000, then how much amount is needed to manufacture z number of products?

I just arrived back from an entry test (for a bank) and this was the first question in the math section. Sorry I don't remember the answer but during test, non of the answers seemed right. I lost a lot of time on this question. Please help me crack it. The answer that I got was

SPOILER: 1000x + y(z-x)

Please help me crack this problem.

CB

[e.cartman]

I think right answer is 1000x+y(z-1000)

[chestnut.cc]

i second cartman...

[computer-bot]

1000x + y(z-x)

Please help me crack this problem.

CB

I think right answer is 1000x+y(z-1000)

Sorry for the mistake. e.cartman is right. 1000x+y(z-1000) should be the right answer. I must get some sleep. I've been up for about 23 hours.

CB

[e.cartman]

yeah, reboot yourself computer.

[boldwolf]

guys... the question said x for the first 1000 units, not x per unit for the first 1000 units or x for each of first 1000 units

i think it should be x + (z-1000)y

[e.cartman]

I agree with boldwolf. It should be x + (z-1000)y since problem does not state x as cost per unit. Thanks boldwolf!

[chestnut.cc]

i second boldwolf... :s

[rakibeeebuet]

i think computer bot is wrong. it will be:
1000x+(z-1000)y

[crony]

I agree with x + (z-1000)y