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    Two unbiased tetrahedral dice each have four faces numbered 1, 2, 3 and 4. The two dice are thrown together and the sum of the numbers on the faces on which they land is noted. Find the expected number of occasions on which this sum is 7 or more when the dice are thrown together 200 times.
    Sol. I got 37.5 by finding the prob and multiplying by 200 that's 3/16*200
    As it says Expected number so can we write 38 or 37. Will that be correct or we just have to leave the answer as 37.5 without rounding?
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    (Original post by kundanad)
    Two unbiased tetrahedral dice each have four faces numbered 1, 2, 3 and 4. The two dice are thrown together and the sum of the numbers on the faces on which they land is noted. Find the expected number of occasions on which this sum is 7 or more when the dice are thrown together 200 times.
    Sol. I got 37.5 by finding the prob and multiplying by 200 that's 3/16*200
    As it says Expected number so can we write 38 or 37. Will that be correct or we just have to leave the answer as 37.5 without rounding?
    What's your working for getting the 3/16 (which is incorrect)?

    Edit: See below.
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    (Original post by ghostwalker)
    What's your working for getting the 3/16 (which is incorrect)?
    Oh really. I did by first finding the sum. It says the sum is 7 or more so there is 2 'seven' and 1 'eight' from the outcomes and got prob 3/16.
    Thats not right then but the answer I got is right. What is the correct way?
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    (Original post by kundanad)
    Oh really. I did by first finding the sum. It says the sum is 7 or more so there is 2 'seven' and 1 'eight' from the outcomes and got prob 3/16.
    Thats not right then but the answer I got is right. What is the correct way?
    Doh! I missed the "or more" bit. 3/16 is correct.

    I would leave it as 37.5, the expectaction of the number of times.
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    (Original post by ghostwalker)
    Doh! I missed the "or more" bit. 3/16 is correct.

    I would leave it as 37.5, the expectaction of the number of times.
    Oh okay. Thanks. Does marks be reduced if rounded?
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    (Original post by kundanad)
    Oh okay. Thanks. Does marks be reduced if rounded?
    Sorry, can't comment on markschemes.
 
 
 
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