Hi, im trying to solve a question on a past paper; here is one that is very similar to it- http://www.gcsemathspastpapers.com/images/p5j04q19.htm [Broken](adsbygoogle = window.adsbygoogle || []).push({});

Im presuming the probability of blue marbles is 7/(k+7)

On part (d) would i have to do something like:

7/(k+7) x k/(k+7) = 4/9 ?

Ive tried the above equation but it doesnt seem to work out seeing as it doesnt give me any square numbers as the LCM becomes 9(k+7)

any help would be much appreciated.

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# Square numbers probability help

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