Question Number 128103 by byaw last updated on 04/Jan/21 $$ \\ $$$$\mathrm{A}\:\mathrm{box}\:\mathrm{contains}\:\mathrm{4}\:\mathrm{black}\:\mathrm{5}\:\mathrm{white} \\ $$$$\mathrm{and}\:\mathrm{6}\:\mathrm{red}\:\mathrm{shirts}.\:\mathrm{3}\:\mathrm{are}\:\mathrm{drawn}\:\mathrm{from} \\ $$$$\mathrm{the}\:\mathrm{box}\:\mathrm{one}\:\mathrm{after}\:\mathrm{the}\:\mathrm{other}\: \\ $$$$\mathrm{without}\:\mathrm{replacement}.\:\mathrm{Find}\:\mathrm{the} \\ $$$$\mathrm{proability}\:\mathrm{that}\:\mathrm{two}\:\mathrm{of}\:\mathrm{the}\:\mathrm{same} \\ $$$$\mathrm{color}\:\mathrm{and}\:\mathrm{one}\:\mathrm{a}\:\mathrm{different}\:\mathrm{color}. \\ $$ Answered…
Question Number 61856 by mr W last updated on 10/Jun/19 Commented by mr W last updated on 10/Jun/19 $${point}\:{P}\:{is}\:{randomly}\:{selected}\:{in}\:{a} \\ $$$${triangle}\:{with}\:{side}\:{lengthes}\:{a},{b},{c}. \\ $$$$\left(\mathrm{1}\right)\:{find}\:{the}\:{average}\:{value}\:{of}\:{the}\:{sum} \\ $$$${of}\:{distances}\:{from}\:{P}\:{to}\:{the}\:{vertexes}.…
Question Number 192622 by sg74656 last updated on 23/May/23 $$\frac{\mathrm{3}}{\mathrm{2}}\mathrm{cos}^{−\mathrm{1}} \sqrt{\frac{\mathrm{2}}{\mathrm{2}+\pi^{\mathrm{2}} }}+\frac{\mathrm{1}}{\mathrm{4}}\mathrm{sin}^{−\mathrm{1}} \frac{\mathrm{2}\sqrt{\mathrm{2}\pi}}{\mathrm{2}+\pi^{\mathrm{2}} }+\mathrm{tan}^{−\mathrm{1}} \frac{\sqrt{\mathrm{2}}}{\pi} \\ $$ Answered by witcher3 last updated on 24/May/23 $$\mathrm{nice}\:\mathrm{one}\:\mathrm{tchek}\:\mathrm{please}\:\mathrm{the}\:\mathrm{expression}\:\mathrm{if}\:\mathrm{it}\:\mathrm{is}\:\mathrm{correct}…
Question Number 192376 by Spillover last updated on 16/May/23 $${Find}\:{the}\:{first}\:{four}\:{moment}\:{of}\:{the} \\ $$$${binomial}\:{distribution} \\ $$$$ \\ $$ Terms of Service Privacy Policy Contact: info@tinkutara.com
Question Number 192377 by Spillover last updated on 16/May/23 $${The}\:{probability}\:{density}\:{function}\:{f}\left({x}\right) \\ $$$$\:{of}\:{a}\:{variable}\:{x}\:{is}\:{given}\:{by}\: \\ $$$${f}\left({x}\right)=\begin{cases}{{kx}\mathrm{sin}\:\pi{x}\:\:\:\:\:\mathrm{0}\leqslant{x}\leqslant\mathrm{1}}\\{\mathrm{0}\:{for}\:{all}\:{value}\:{of}\:{x}}\end{cases} \\ $$$${Show}\:{that}\:{k}=\pi\:\:{and}\:{deduce}\:{that}\:{mean}\: \\ $$$${and}\:{the}\:{variance}\:{of}\:{the}\:{distribution}\:{are} \\ $$$$\left(\mathrm{1}−\frac{\mathrm{4}}{\pi^{\mathrm{2}} }\right)\:{and}\:\frac{\mathrm{2}}{\pi^{\mathrm{2}} }\left(\mathrm{1}−\frac{\mathrm{8}}{\pi^{\mathrm{2}} }\right) \\ $$…
Question Number 192375 by Spillover last updated on 16/May/23 $${Show}\:{that}\:{E}\left({Z}\right)=\mathrm{0}\:\:\:{and}\:{Var}\left({Z}\right)=\mathrm{1}\:{where} \\ $$$${Z}\:{is}\:{the}\:{standard}\:{normal}\:{variable} \\ $$ Answered by mehdee42 last updated on 16/May/23 $${We}\:{know}\:\because\:\:\:{Z}=\frac{{x}−\mu}{\sigma}\:\:\: \\ $$$$\&\:\:{E}\left({kx}\right)={kE}\left({x}\right)\:\:\&\:\:{E}\left({x}+{k}\right)={E}\left({x}\right)+{k}\:\:;\:{k}\in\mathbb{R} \\…
Question Number 192255 by Spillover last updated on 01/Feb/24 $${If}\:\theta\:{be}\:{the}\:{acute}\:{angle}\:{between}\:{two}\:{regression} \\ $$$${line}\:{in}\:{the}\:{case}\:{of}\:{two}\:{variables}\:{x}\:{and}\:{y} \\ $$$${Show}\:{that} \\ $$$$\:\:\mathrm{tan}\:\theta=\frac{\mathrm{1}−{r}}{{r}}.\frac{\sigma_{{x}} \sigma_{{y}} }{\sigma_{{x}} ^{\mathrm{2}} +\sigma_{{y}} ^{\mathrm{2}} }\:\:\: \\ $$$${where}\:\:{r},\sigma_{{x}} ,\sigma_{{y}}…
Question Number 192254 by Spillover last updated on 01/Feb/24 $${Establish}\:{the}\:{formular}\:\: \\ $$$$\sigma_{{x}−{y}} ^{\mathrm{2}} =\sigma_{{x}} ^{\mathrm{2}} +\sigma_{{y}} ^{\mathrm{2}} −\mathrm{2}{r}\sigma_{{x}} \sigma_{{y}} \:\: \\ $$$${where}\:{by}\:{r}\:{is}\:{the}\:{correlation} \\ $$$${coefficient}\:{between}\:{x}\:{and}\:{y} \\…
Question Number 192118 by Red1ight last updated on 08/May/23 $$\mathrm{given}\:\mathrm{points}\:\left({a},{b}\right)\:\mathrm{where}\:{a},{b}\:\in\mathbb{R} \\ $$$$\mathrm{how}\:\mathrm{to}\:\mathrm{get}\:\mathrm{the}\:\mathrm{best}\:\mathrm{fit}\:\mathrm{parabola}\:\mathrm{that}\:\mathrm{go}\:\mathrm{through}\:\mathrm{the}\:\mathrm{origin} \\ $$$$\mathrm{and}\:\mathrm{open}\:\mathrm{downward}\:\left(\mathrm{coefficient}\:\mathrm{of}\:{x}^{\mathrm{2}} \:\mathrm{is}\:\mathrm{negative}\right)? \\ $$ Terms of Service Privacy Policy Contact: info@tinkutara.com
Question Number 192112 by Spillover last updated on 08/May/23 $${prove}\:{that}.\:\:\:\:\:\:\:\mathrm{0}!=\mathrm{1} \\ $$ Commented by Frix last updated on 08/May/23 $$\mathrm{I}\:\mathrm{think}\:\mathrm{it}'\mathrm{s}\:\mathrm{defined}\:\mathrm{0}!=\mathrm{1}\: \\ $$$$\mathrm{There}'\mathrm{s}\:\mathrm{the}\:\mathrm{idea}\:\mathrm{of}\:\mathrm{the}\:“\mathrm{Empty}\:\mathrm{Product}'' \\ $$$$\:\:\:\:\:\mathrm{It}'\mathrm{s}\:\mathrm{obvious}\:\mathrm{that}\:\mathrm{the}\:“\mathrm{Empty}\:\mathrm{Sum}''=\mathrm{0} \\…