Maths Help- KS3

11 Plus Maths – Preparation and Information

Moderators: Section Moderators, Forum Moderators

Post Reply
11 Plus Mocks - Practise the real exam experience - Book Now
rejim2
Posts: 92
Joined: Thu Mar 17, 2011 1:58 pm

Maths Help- KS3

Post by rejim2 »

Hello all,

Any help much appreciated!

Question-
The yearly change in the yield of one particular crop in our area over the past 2 years was 20% increase followed by 20% decrease. What is the total percentage change over two years?

Thanks,
Ladymuck
Posts: 1240
Joined: Wed Jul 01, 2009 2:04 pm

Re: Maths Help- KS3

Post by Ladymuck »

Start with 100.
20% increase in year 1 gives you 120.
20% decrease is year 2 gives you a decrease of 24, so net result of 96.

In maths terms, I would describe the change as (1+.2)*(1-.2)=.96, so a total chance of 1-.96= a reduction by 4%
rejim2
Posts: 92
Joined: Thu Mar 17, 2011 1:58 pm

Re: Maths Help- KS3

Post by rejim2 »

Thankyou Lady muck! great... the choice answers were
-4%, -1% , 0% , 1% and 4%.
Post Reply
11 Plus Platform - Online Practice Makes Perfect - Try Now