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A red die and a white die are tossed. Determine the probability of rolling a sum greater than 8, to the nearest hundredth.

my work: First, it is important to note that the results of the two dice are independent (that is, they do not affect each other). Thus, there are 6*6=36 possible outcomes.

Next, we must determine how many successes exist, because Probability=(number of successes)/(number of possibilities).

                   Second Die
     N    1   2   3   4   5   6 
     ---------------------------

F 1 | 2 3 4 5 6 7 i D 2 | 3 4 5 6 7 8 r i 3 | 4 5 6 7 8 9 s e 4 | 5 6 7 8 9 10 t 5 | 6 7 8 9 10 11 6 | 7 8 9 10 11 12

P(sum>8) = 10 successes out of 36 possibilities = 10/36 = 5/18 =0.28

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Tanvir Joshi
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  • is this the correct answer? – Tanvir Joshi Jun 09 '20 at 16:09
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    It looks fine to me but do use different titles for your questions – UnsinkableSam Jun 09 '20 at 16:17
  • @TanvirJoshi It is understable if you can't do this when writing a question, but when you are solving these answers by yourself, draw a sample space diagram! It makes a lot of these problems go away. This question can in essence can be stripped down into: count the number of possibilities that give you $9$ or more, and divide by $36$. Then round your answer. Your approach is essentially the same but in my opinion is more liable to error. – Joe Jun 09 '20 at 16:26
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    It is not recommended to solve things by brute force like this. You will likely make a mistake in the future by incorrectly manually counting things. Especially when there are tens of thousands of possibilities and everything starts to blur together on paper. Far better to find a pattern which can be used to organize your count and reduce chance of a mistake. – JMoravitz Jun 09 '20 at 16:28
  • ok,i will fix the way i fomatted it,but is the answer correct/ – Tanvir Joshi Jun 09 '20 at 16:31
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    That and, I really do need to voice my agreement with JustWandering's comment. You have posted six questions and every single one of them is titled "my way of solving this probability question given below" or some slight variation. This is unacceptable! Read this meta post for how to choose a good title and why a good title is important. – JMoravitz Jun 09 '20 at 16:32
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    This is not only for our benefit as people trying to provide help, being able to more quickly identify questions which we can help with, but also provide benefit to future users for finding questions when searching that match the same question they are wanting answered. It also helps you! If you want to look through your post history and revisit the answer to one of your old questions, if they are all labeled the same you will have a hard time remembering which was which to click on the correct one. Naming them all differently with text specific to that problem will help tremendously. – JMoravitz Jun 09 '20 at 16:35
  • ok i will make sure for future questions,and will fix the old ones, – Tanvir Joshi Jun 09 '20 at 16:36
  • is my answer correct though? – Tanvir Joshi Jun 09 '20 at 16:37
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    As mentioned already, it is correct but the technique used is risky and prone to typos, accidents, and human error in general and is infeasible to use in sufficiently larger more complicated problems. – JMoravitz Jun 09 '20 at 16:38
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    Can someone explain the work? I have no clue what it means. – scoopfaze Jun 09 '20 at 20:34
  • A very similar question was asked here. Use $n=2$, $m=6$, and add up the results from $S=9$ to $S=12$, divide by the total number of possible rolls $36$, and you're done. – K.defaoite Jun 09 '20 at 23:12

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