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    A fire station has from zero to five calls each day. It is estimated that the probability distribution for the number of calls is given below. Determine the expected number of service calls.

    Number of calls012345Probability0.100.100. 200.350.100.15







    So i did 0x0.1+1x0.1+2x0.2+3x0.35+4x0.1+5 x0.15 which gives me 2.7

    what have i done wrong?
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    (Original post by will'o'wisp2)
    A fire station has from zero to five calls each day. It is estimated that the probability distribution for the number of calls is given below. Determine the expected number of service calls.

    Number of calls012345Probability0.100.100. 200.350.100.15


    So i did 0x0.1+1x0.1+2x0.2+3x0.35+4x0.1+5 x0.15 which gives me 2.7

    what have i done wrong?
    Can't see anything wrong, other than the fact your table of probabilities is virtually unreadable.
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    (Original post by ghostwalker)
    Can't see anything wrong, other than the fact your table of probabilities is virtually unreadable.
    BRILLIANT LET ME FIX THAT FOR YOU

    Number of calls 0 .........1 ............2 ...........3 ...........4 .............5
    Probability ........0.10 .....0.10 ......0. 20 .....0.35 .....0.10 .....0.15
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    (Original post by will'o'wisp2)
    BRILLIANT LET ME FIX THAT FOR YOU

    Number of calls 0 .........1 ............2 ...........3 ...........4 .............5
    Probability ........0.10 .....0.10 ......0. 20 .....0.35 .....0.10 .....0.15
    Let me fix that for you!

    \begin{array}{|c|c|} \text{Number of calls} & \text{Probability} \\ \hline 0 & 0.10 \\ 1 & 0.10 \\ 2 & 0.20 \\ 3 & 0.35 \\ 4 & 0.10 \\ 5 & 0.15 \\ \hline \end{array}

    Motto: Learn LaTeX.
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    (Original post by ghostwalker)
    Let me fix that for you!

    \begin{array}{|c|c|} \text{Number of calls} & \text{Probability} \\ \hline 0 & 0.10 \\ 1 & 0.10 \\ 2 & 0.20 \\ 3 & 0.35 \\ 4 & 0.10 \\ 5 & 0.15 \\ \hline \end{array}

    Motto: Learn LaTeX.
    bloody heck, nice \LaTeX

    PRSOM
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    (Original post by ghostwalker)
    Let me fix that for you!

    \begin{array}{|c|c|} \text{Number of calls} & \text{Probability} \\ \hline 0 & 0.10 \\ 1 & 0.10 \\ 2 & 0.20 \\ 3 & 0.35 \\ 4 & 0.10 \\ 5 & 0.15 \\ \hline \end{array}

    Motto: Learn LaTeX.
    good lord i don't know how to do tables xD

    only recently learned how to make an augemnted matrix D:
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    the expected value is 2.7 as you say.
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    (Original post by the bear)
    the expected value is 2.7 as you say.
    good ol trusty bear
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    (Original post by will'o'wisp2)


    what have i done wrong?
    Why do you think this is wrong?
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    (Original post by Muttley79)
    Why do you think this is wrong?
    my lack of brain cells
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    (Original post by will'o'wisp2)
    my lack of brain cells
    OK - nothing serious then ...

    Did you confuse it with probability and 'expect' an answer less than 1?

    E(X) = mean value
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    (Original post by Muttley79)
    OK - nothing serious then ...

    Did you confuse it with probability and 'expect' an answer less than 1?

    E(X) = mean value
    is ex the mean value? so there's no difference between the expected value and mean value?

    it's just that i got 2.8 the first time i put it in the calculator >.>
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    (Original post by will'o'wisp2)
    is ex the mean value? so there's no difference between the expected value and mean value?

    it's just that i got 2.8 the first time i put it in the calculator >.>
    Think about how you find the mean from a frequency table - for E(X) you do the same but total frequency = 1 because it's the total probability.
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    (Original post by Muttley79)
    Think about how you find the mean from a frequency table - for E(X) you do the same but total frequency = 1 because it's the total probability.
    you add all the values divide by the number of entries

    for expected you multiply the entry by the probability and all those all up...
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    (Original post by will'o'wisp2)
    you add all the values divide by the number of entries

    for expected you multiply the entry by the probability and all those all up...
    Which is the same thing ... E(X) = mean value
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    (Original post by Muttley79)
    Which is the same thing ... E(X) = mean value
    i see ye
 
 
 
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