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How do you do this question ? Don't you do 10 * 1.05 so it is A ? Also it is inelastic the demand, so surely the total revenue will rise.

A product has a price elasticity of demand of –0.5. If the price of this product increases by
10%, then total revenue will
A rise by more than 10%.
B rise by less than 10%.
C fall by more than 10%.
D fall by less than 10%
Reply 1
PeD = % change in Q demanded / % change in P

Therefore, the % change in Q demanded = PeD * % change in P
(As Q demanded is what the question is really asking about)

Q demanded = PeD * % change in P = 0.5 * 10 = 5%. The answer is B.

I'm not quite sure where you've got the 1.05 from..?
Reply 2
Original post by NikolaT
PeD = % change in Q demanded / % change in P

Therefore, the % change in Q demanded = PeD * % change in P
(As Q demanded is what the question is really asking about)

Q demanded = PeD * % change in P = 0.5 * 10 = 5%. The answer is B.

I'm not quite sure where you've got the 1.05 from..?


Hi thanks, how did you know how to rearrange the equation ? How do you do it the right way ?
Reply 3
Original post by furquan
Hi thanks, how did you know how to rearrange the equation ? How do you do it the right way ?


Did you do GCSE Maths or Physics? It's rearrangement in the same way.

x = y/z

y = x * z

:smile:
Original post by furquan
How do you do this question ? Don't you do 10 * 1.05 so it is A ? Also it is inelastic the demand, so surely the total revenue will rise.

A product has a price elasticity of demand of –0.5. If the price of this product increases by
10%, then total revenue will
A rise by more than 10%.
B rise by less than 10%.
C fall by more than 10%.
D fall by less than 10%

Here's how I approached this question (note that Nikola calculated just the %change in QD rather than TR

PED = %changeP/%changeQd
so rearranging gives you %changeQd = -5%

But we want changes in TR, so...

let p1 = 1 and p2 = 1.1 (10% increase)
let q1 = x and q2 = 0.95x (5% decrease)

therefore since TR = PQ, TR1 = x and TR2 = 1.045x

So the rise in TR is 4.5%, which is < 10%, so B is the answer.
Reply 5
Hi since PED is always negative do you ignore the minus sign for -0.5 ? So 0.5 * 10 = 5 so it is B

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