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    Can anyone please help with the following question, I am struggling to model my answer. Once that bit is done, I can solve the rest.

    "A machine cuts a very long plastic tube into short tubes. The length of the short tube is modelled by a normal distribution with mean m and standard deviation 0.25cm. The value of m can be set by adjusting the machine. Find the value of m for which the probability is 0.1 that the length of a short tube, picked at random, is less than 6.50cm."

    Thanks!
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    (Original post by ninuzu)
    Can anyone please help with the following question, I am struggling to model my answer. Once that bit is done, I can solve the rest.

    "A machine cuts a very long plastic tube into short tubes. The length of the short tube is modelled by a normal distribution with mean m and standard deviation 0.25cm. The value of m can be set by adjusting the machine. Find the value of m for which the probability is 0.1 that the length of a short tube, picked at random, is less than 6.50cm."

    Thanks!
    P(X<6.50)=0.1 therefore we can find P(Z<... , in terms of m, try it. Drawing a graph may help too.
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    (Original post by raiden95)
    P(X<6.50)=0.1 therefore we can find P(Z<... , in terms of m, try it. Drawing a graph may help too.
    I did that, but it doesn't come up with the correct answer. I then thought that I should look for 0.1 in the normal distribution tables, but they start at 0.5..
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    The textbook answer is 6.82
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    Never mind I've just worked it out.
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    (Original post by ninuzu)
    Never mind I've just worked it out.
    Which exam board is this? because I have not started S2
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    (Original post by raiden95)
    Which exam board is this? because I have not started S2
    OCR. I worked it out by finding 0.95 in the normal tables and making that answer a minus sign. Then solving normally.
 
 
 
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Updated: December 31, 2012
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