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# Someone please solve this for me. watch

1. Six sided die is biased that even numbers are three times as likely odd numbers. What is the probability of observing prime number on one roll of this die?
2. (Original post by a_09)
Six sided die is biased that even numbers are three times as likely odd numbers. What is the probability of observing prime number on one roll of this die?
If odds land with probability , then evens land with probability . And thus we have which is the total probability.

Work from there.
3. (Original post by a_09)
Six sided die is biased that even numbers are three times as likely odd numbers. What is the probability of observing prime number on one roll of this die?
Think about what you would need to roll to get a prime number. That tells you what you need to work out the probability of happening.
From there you need to work out the probability of rolling that number.
The total probabilities need to add up to one.

See if that helps.
4. (Original post by RDKGames)
If odds land with probability , then evens land with probability . And thus we have which is the total probability.

Work from there.
I still dont get it. Please, can you show me the working?
I get that the even numbers are 2,4 and 6 whereas 2 is the only number thats prime as well as even. But how do we find the probability then?
Options given are:
i)1/2
ii)3/4
iii)5/6
iv)5/12
5. (Original post by a_09)
I still dont get it. Please, can you show me the working?
I get that the even numbers are 2,4 and 6 whereas 2 is the only number thats prime as well as even. But how do we find the probability then?
Options given are:
i)1/2
ii)3/4
iii)5/6
iv)5/12
1) What’s the probability of getting an odd number?
2) What’s the probability of getting an even number?
3) What are all the possible primes?

Try to answer these questions and you should be able to solve it
6. (Original post by Anna1029)
1) What’s the probability of getting an odd number?
2) What’s the probability of getting an even number?
3) What are all the possible primes?

Try to answer these questions and you should be able to solve it
So according to me, answer to all three of them should be 1/3 because (for each of them):
i) Odd numbers are three and total numbers are 6, that makes 3/6.
ii) Even numbers are three and total numbers are 6, that makes 3/6.
iii) Prime numbers are three and total numbers are 6, that makes 3/6.
7. (Original post by a_09)
So according to me, answer to all three of them should be 1/3 because (for each of them):
i) Odd numbers are three and total numbers are 6, that makes 3/6.
ii) Even numbers are three and total numbers are 6, that makes 3/6.
iii) Prime numbers are three and total numbers are 6, that makes 3/6.
And the die is biased.
8. (Original post by a_09)
So according to me, answer to all three of them should be 1/3 because (for each of them):
i) Odd numbers are three and total numbers are 6, that makes 3/6.
ii) Even numbers are three and total numbers are 6, that makes 3/6.
iii) Prime numbers are three and total numbers are 6, that makes 3/6.
No. Look at my last post, you can determine the probability of getting an even number and hence the probability of an odd number. It's not 50/50 since the die is biased!

To get the prob of getting a prime, well these are just 2,3, and 5, so just use their probabilities to get the answer.
9. it is the same as throwing a 12 sided die with the numbers 1 2 2 2 3 4 4 4 5 6 6 6...
10. Oh yeah, i get it. Thank you so much!
11. (Original post by a_09)
So according to me, answer to all three of them should be 1/3 because (for each of them):
i) Odd numbers are three and total numbers are 6, that makes 3/6.
ii) Even numbers are three and total numbers are 6, that makes 3/6.
iii) Prime numbers are three and total numbers are 6, that makes 3/6.
But you have to remember that the die is biased so the probability of throwing an even number is different to that of an odd number.
Work out each of those probabilities

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