maths probability solution please
Moderators: Section Moderators, Forum Moderators
Re: maths probability solution please
similar question that is eating my brains...
A farmer has 100 sheep in a field. 60% of the sheep are ewes, and the rest are rams. 80% of the sheep are lambs and the rest are mature sheep. 75% of the sheep are white and rest are black.
How many sheep in the field are likely to be black, mature rams?
I really need to know how to work these out. Poor kids how can they do this?
Please help me.
A farmer has 100 sheep in a field. 60% of the sheep are ewes, and the rest are rams. 80% of the sheep are lambs and the rest are mature sheep. 75% of the sheep are white and rest are black.
How many sheep in the field are likely to be black, mature rams?
I really need to know how to work these out. Poor kids how can they do this?
Please help me.
Re: maths probability solution please
100 sheepidl wrote:A farmer has 100 sheep in a field. 60% of the sheep are ewes, and the rest are rams. 80% of the sheep are lambs and the rest are mature sheep. 75% of the sheep are white and rest are black.
How many sheep in the field are likely to be black, mature rams?
25% are black ie 25
20% are mature ie 1/5 of 25 = 5
40% are rams 5 x 0.4 = 2
I would go in steps like this but you should get a whole number answer!
Re: maths probability solution please
But both questions are (it seems) implicitly assuming the independence of the different factors, which is by no means certain. For example, in the first case, if the favourite author writes only non-fiction (Bill Bryson maybe!) then all 20 of them could be paperbacks, or none of them. Badly worded (putting on my statistical hat) . But if the favourite author writes fiction, the answer must be zero anyway. More information needed!
Re: maths probability solution please
Yes..for the sheep question, answer is 2
Re: maths probability solution please
Yep exactly, very poor question ... at least the sheep one is clearer.
Re: maths probability solution please
I see no problem with this one ...idl wrote:Yes..for the sheep question, answer is 2
Re: maths probability solution please
I missed the fact to work it from back every step
Re: maths probability solution please
And doesn't involve the candidate indulging in the unlicensed slaughter of farm animals in the middle of the exam .Guest55 wrote:Yep exactly, very poor question ... at least the sheep one is clearer.
Outside of a dog, a book is a man's best friend. Inside of a dog it's too dark to read.Groucho Marx
Re: maths probability solution please
Yes, take each statement in turn but this only works if the attributes are independent so that's why the book one is flawed.
Re: maths probability solution please
Toadmum: thanks for bringing smile on my face, i was in a great head rush/spin etc
Thanks to Guest55 for prompt responses.
Thanks all, i think i got hang of these now
Thanks to Guest55 for prompt responses.
Thanks all, i think i got hang of these now