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Not sure if I am losing it but this seems like nonsense.
[url= http://www.bbc.co.uk/news/magazine-37178008 ]BBC Linky[/url]
MATHS: A pet shop had 40 rabbits.
22 were male.
The others were female.
The shop sold 10 of the rabbits.
The probability that a rabbit picked at random is male is now 1/2 (0.5).
How many female rabbits were sold?
Choices 3, 4 or 5.
BBC explanation!!!!!
It's 3. There were 18 rabbits (40-22=18) originally. To have a 1/2 (one-in-two) chance of picking out a male after 10 were sold, there would need to be 15 of each sex - so 18-15=3.
Did you fail English too..... 😉
I make it 3 female rabbits sold
There are (40-10)=30 rabbits post-sale.
There is now a 50:50 chance of one being male, ie an equal number. Ergo, there are now 15 male and 15 female.
There was originally (40-22)=18 female rabbits. There is now 15 female rabbits. 18-15=3.
Capiche?
[img] https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTyYZMBEEqLKIQVgfjx_6OHkZ0iFPqW33jUuRjvvROfdQGRvTaFnw [/img]
Works for me now, completely thrown by the first statement of the answer that there were 18 rabbits originally!
Big thanks, makes sense.
@wors stealthy edit - long time since I was at school and rely too much on spell checker.
Good job you don't have to sit one those 'oh so easy' GCSEs then. That's not tricky in the big scheme of things.
I genuinely did OK on the others with a lucky guess on one. But I don't think the exams are easy! Puts the young people under pressure and expectation.
Maybe not that tricky but if you get to over thinking then it is.