9-1 Edexcel Maths GCSE questionWatch this thread
Alex wants to find out how many ducks there are in a park.
One day he puts a tag on each of 30 of the ducks.
The next day he catches 40 ducks.
8 of these ducks have tags on them.
(i) Work out an estimate for the number of ducks in the park
Alex assumed the none of the tags fell off during the night.
(ii) If Alex's assumption is wrong, explain how this could affect your answer to part (i).
For the second part if any of the tags fell off we can assume that he would have found more than 8 ducks with tags on, how does this affect x, you can use the example of 30/x=9/40 to find this out.
Set up ratios and proportional equations e.g.
30/x = 8/40
30/x = 1/5
Thus x = 150. So estimated 150 around.
His assumption is that none of the tags fell therefore the proportion is correct. However, if any of the tags fell - it could affect the accuracy of his assumption and obviously in the second equation, there would >8/40 for the second equation. To explain this to you, let's assume that 2 fell therefore the actual number would be 10/40 or 1/4. Meaning 30/x = 1/4 therefore x = 120. So it would mean that there's less totan animals.
Again, these are just my logical reasoning - my board doesn't include this spec.