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Question Number 182331 by ali009 last updated on 07/Dec/22
$${a}\:{box}\:{contains}\:\mathrm{5}\:{white}\:{balls}\:{and}\:{some}\:{black} \\ $$$${balls}.\:{if}\:{the}\:{probability}\:{of}\:{drawing}\:{a}\:{black} \\ $$$${ball}\:{from}\:{the}\:{bag}\:{is}\:{twice}\:{the}\:{prbability} \\ $$$${of}\:{drawimg}\:{a}\:{white}\:{ball}\:{then}\:{find}\:{number} \\ $$$${of}\:{black}\:{balls}. \\ $$
Answered by Acem last updated on 07/Dec/22
$$\:{Num}.\:{black}\:{balls}=\:\mathrm{10}\:\left({mentally}\right) \\ $$$$\:{The}\:{solution}: \\ $$$$\:{P}\left({B}\right)=\:\frac{\left({T}−\:{w}\right)}{{T}}=\:\frac{\mathrm{2}\:{w}}{{T}}\:\Leftrightarrow\:\:\frac{{T}−\mathrm{5}}{{T}}=\:\frac{\mathrm{10}}{{T}}\:,\:\:\:{T}=\:\mathrm{15},\:{B}=\:\mathrm{10} \\ $$