What is the probability of exactly two accidents on at least one day of a week, in case of 7 indistinguishable accidents per week If 7 accidents (all are indistinguishable i.e we care only about whether accident happen or not, not the details of it) happen in a week.  What is the probability of exactly two accidents on at least one day of a week.  My solution is given below  $$ \frac{1}{13 \choose 6} \Bigg[{7 \choose 1}{10 \choose 5} - {7 \choose 2} {7 \choose 4} + {7\choose 3} 4 \Bigg] = 0.681 $$  I used the equation that number of ways $r$ balls can be arranged in $n $ cells in ${n+r-1 \choose n-1}$ distinguishable ways.  Is it correct ?
probability that exactly two accidents happen in any day of a week if 7 accidents happen in a week If 7 accidents happen in a week, what is the probability that exactly 2 accidents happen in any day of the week.  I tried to work it this way.  2 accidents out of 7 can be taken in ${7}\choose{2}$$= 21$.  Now this can happen in any of the 7 days, so we have $7 \times 21$.  Now, the remaining 5 can happen in $6^5$ ways.  So the probability is  $\frac{7\times 21 \times 6^5}{7^7} = \frac{3 \times 6^5}{7^5}$   But this gives me a value greater than 1.   I know I am doing something wrong.  Can anyone help me ?
After starting Ubuntu, I see the following lines. Should I be worried?  /dev/sda6: recovering journal /dev/sda6: clean, 355773/1835008 files, 470404803/7335680 blocks Get full URL (including querystring) from an apex REST endpoint If $11z^{10}+10iz^9+10iz-11 = 0$. Then possible value of $\mid z \mid,$ is If $11z^{10}+10iz^9+10iz-11 = 0$. Then possible value of $\mid z \mid,$ is  $\bf{My\; Try::}$ Given $11z^{10}+10iz^9+10iz-11 = 0\Rightarrow \displaystyle z^9 = \frac{11-10iz}{11z+10i}.$  Now Put $z = x+iy\;,$ we get $\displaystyle (x+iy)^9 = \frac{11-10i(x+iy)}{11(x+iy)+10i} = \frac{(11+10y)-10ix}{11x+i(10+11y)}$  Now i did not understand how can i solve it,  Help Required  Thanks How can I take a photo which shows the skyline and the person who is standing around six feet away from the camera with proper lighting at night?   For taking just the skyline I've used long shutter speed and it turned out great, but when including a person on it, the person becomes  blurry because it's impossible for a person to remain static for that long.   Ps.  I do have two flashes, 35mm prime lens as well as 18-300mm zoom lenses as well. The camera I use is Nikon D7200. Is there a way to change the restrictions passcode on an iPhone without restoring the phone? I haven't forgotten the passocde; I just want to change it. I've searched the net for such information and found different command lines, like these ones:  sudo apt-get remove application sudo apt-get remove application*  sudo apt-get remove --purge application sudo apt-get remove --purge application*  sudo apt-get purge application sudo apt-get purge application*   So, what is the correct way? Is it necessary to use that "*"?  After that, I also found these commands:  sudo updatedb sudo locate application sudo rm -rf (file/folder name) Create taxonomy terms on the fly Do we really need polynomials (In contrast to polynomial functions)? Shared email on 2 Facebook accounts is stopping access to both accounts My husband wanted me to set up a Facebook account for him and I accidentally used our shared email address, which is set against my own account.  Since then, neither of us has been able to log in, so I can't alter any settings.  Can anyone advise how to resolve this please? Is there any API function for shutting down Windows while installing any pending updates? I have, not one but two microSD cards that my phone (Samsung Galaxy Young, Gingerbread OS) seem to have broken. One is 1GB and the other is 2GB. The 1GB one won't be formatted.  When I put the 1GB one into the computer the computer prompts for a formatting. I don't care for the content so I tried to format it, but to no avail; the format fails and I have no idea what to do to make it work again.  I tried using the SDformatter software, but it can't format the card as it is write protected. I'm googling to solve it but so far no success.  My computer OS is win7 if that's of any relevance. How to run Java code using Java code? Badge overflow on users with too many badges When a user has &quot;too much&quot; reputation and &quot;too many&quot; badges, the design of the user card breaks:    The badge counters overflowing to another line. Can anything be done about this? For example, expanding the rep and badges to their own lines:  NameRepBadges Find the general solution of $4u_{xx}+5u_{xy}+u_{yy}+u_x+u_y=2$ How do I solve the following second order partial differential equation?  $4u_{xx}+5u_{xy}+u_{yy}+u_x+u_y=2$  I have classified the equation to be hyperbolic and changed variables to obtain the canonical form as $u_{\epsilon\nu}={1\over{3u_\nu}}-{8\over9}$ which I believe is correct but I am struggling to find the general solution? A step by step solution would be appreciated. Any way to open windows from the windows bar using a shortcut? for example to open the first window on the left Ctrl+1, to open the second window on the left Ctrl+2.  Im using xfce4 at this moment, but if under xfce4 is not possible, is there any other desktop environment that permits this?  Since I have several windows open for the same application, I not searching for sortcuts related to the application but as I say below, to the window. Do you have advantage when multiple sources give advantage and only one gives disadvantage? As I understand it:   if you have Advantage from two different sources, you simply have Advantage (no stacking) if you have advantage from one source, and disadvantage from one source, they cancel out.     So what if you have advantage from two or more sources, and disadvantage from one source?  My assumption is that you simply have advantage, or put another way, you have Advantage on a roll when the # of Advantages > # of Disadvantages (and vice versa).  Is that correct? Is there a tag in HTML that will only display its content if JavaScript is enabled? I know &lt;noscript&gt; works the opposite way around, displaying its HTML content when JavaScript is turned off. But I would like to only display a form on a site if JavaScript is available, telling them why they can't use the form if they don't have it.  The only way I know how to do this is with the document.write(); method in a script tag, and it seems a bit messy for large amounts of HTML. Why do modern mountain bike forks no longer use boots on fork stanchions? Older mountain bikes used to have them on the forks, and lefty and headshocks still do. Why have these fallen out of fashion and would putting aftermarket fork boots on your stanchions be productive or not? tikz declare function and babel french option I have 2 partitions (Windows and Ubuntu 13.04) and I am asked which one to boot each time I turn on my computer.  I want to install Ubuntu 13.10 to the entire disk.  I do not mind if all previous Ubuntu/Win data are lost.  How can I do that?