I am really confused because I am currently doing probability homework for one of my classes. I have a set of questions based on the MEGA Millions lottery, but none of the probabilities I’ve created match what is listed on the wikipedia page or the official site when I compute the probabilities myself.
For example, wikipedia currently lists that the probability of earning $2 (a net of $1) is 1 in 75. However, I computed it to be 1 in 46.
I did this my the following equation:
(nCr(56,5)*nCr(1,1))/(nCr(56,5)*nCr(46,1))
The nCr(56,5)s should simplify to 1 leaving the answer to be 1/46. Am I missing something?
Actually I figured out what my problem is. However I’ll leave this question open until someone tells me what the mistake is that I already know.
Also fyi, nCr() is notation for performing combinations in many of the TI calculators and it is easier to use that notation than attempt to display it as most math books show it.
Arnold
Comments
I don’t understand any of the math formulas seeing as how I hate math. But one thing I remember reading one time was the odds of getting just one number isn’t 1 / how many numbers there are. Because there is a chance you are going to get a second number right as well.
P(win)= P(0 wins in the first selection)* P(1 win in the second selection)
P(1 win in the second selection)= 1/46 obviously
but you have to multiply that by P(0 wins in the first selection)
Note that wikipedia states that the probability is approximately 1/75. I “smell” it’s not exactly 1/75 but close to it.
