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maths probability solution please

Posted: Sat Aug 18, 2018 7:57 pm
by idl
Someone please help me how to solve this!!

i have 140 books. i find that 60% of the total number of books are paperbacks. the fiction books make up 0.3 of the total and 1/7 are by my favourite author.
How many books are likely to be paperback, non-fiction by my favourite author?


Thanks in advance.

Re: maths probability solution please

Posted: Sat Aug 18, 2018 8:02 pm
by Guest55
idl wrote: i have 140 books. i find that 60% of the total number of books are paperbacks. the fiction books make up 0.3 of the total and 1/7 are by my favourite author.
How many books are likely to be paperback, non-fiction by my favourite author?
1/7 are by favourite author - 1/7 of 140 = 20

Can you complete it now?

Re: maths probability solution please

Posted: Sat Aug 18, 2018 8:07 pm
by idl
Hi
Thanks for the prompt reply.

I did that bit.
It said 60% paperback --- 84
0.3 of total are fiction --42
1/7 are fav --20

according to Question: likely to be paperback and non-fiction: 84+98(140-42!) by my fav author...dont know what to do after this...

Re: maths probability solution please

Posted: Sat Aug 18, 2018 8:10 pm
by Guest55
I don't think you need to do this - the question is actually a bit vague.

If 0.3 are fiction then 0.7 are non-fiction.

So 20 x 0.7 = 14 would be my answer.

Re: maths probability solution please

Posted: Sat Aug 18, 2018 8:12 pm
by idl
:( ans was given as 8! Im struggling to fig this out :roll:

Re: maths probability solution please

Posted: Sat Aug 18, 2018 8:17 pm
by Guest55
OK we need the paperback ones so we need to find 60% of 14 = 8.4!!

Very dodgy

Re: maths probability solution please

Posted: Sat Aug 18, 2018 8:22 pm
by idl
isn't it!! but options are whole numbers, no deci...

Re: maths probability solution please

Posted: Sat Aug 18, 2018 8:24 pm
by Guest55
Someone has made a mistake with the question as the answer should be a whole number. Can you double check the numbers you posted?

Re: maths probability solution please

Posted: Sat Aug 18, 2018 8:25 pm
by ToadMum
Where on earth did this question come from? :roll:

Re: maths probability solution please

Posted: Sat Aug 18, 2018 8:26 pm
by idl
I checked and read the question many times..this is from Bond 11+ test papers