Recent content by alex07966

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    Question involving pdf of change of variable

    A Geiger counter records the times at which radioactive particles are detected. However, if two particles occur within a short time θ of each other, the second one is not detected. Then, the probability density function of X, the time between successive recorded detections, is f(x) = k...
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    Probability question: blue and cyan balls in an urn

    An urn contains b blue balls and c cyan balls. A ball is drawn at random, its colour is noted, and it is returned to the urn together with d further balls of the same colour. This procedure is repeated indefinitely. i) What is the probability that the second ball drawn is cyan? ii) What is...
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    Proving a group G is isomorphic to D_10

    Question: Let G be a non-abelian group such that the size of G is 10. Prove G is isomorphic to D_10. I have started by saying the elements of G have order 1,2,5 or 10. And then showing how there are no elements of order 10 as that would make it abelian. I then show there is an element x of...
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    How many subgroups of size 5 in A_6 have cyclic elements?

    Ok, I have noticed that <a> = <a^2> = <a^3> = <a^4> for all a in A_6 where a is a 5-cycle. So this means that the number of elements of order 5 must be divided by 4. Hence the answer is 144/4 = 36 subgroups of size 5 in A_6. Is this correct?
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    Non-abelian subgroup of size 6 in A_6

    Thanks a lot. I have found what the subgroup is now: {e, (23)(56), (13)(46), (12)(45), (123)(456), (132)(465)}. I need to justify my answer so I need to show that this is isomorphic to D_6 and therefore is a subgroup. I'll have a go.
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    Non-abelian subgroup of size 6 in A_6

    I need to find just one non-abelian subgroup of size 6 in A_6. I have started by noting that the subgroup must be isomorphic to D_6 and then tried to use the permutations in D_6 that sends corners to corners. I then came across the problem that the reflection elements in D_6 consist of...
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    How many subgroups of size 5 in A_6 have cyclic elements?

    I need to find the number of subgroups of size 5 in A_6. I have started by noting that as the subgroup size is 5, a prime, the subgroups must be cyclic. I have worked out that there are 144 elements of order 5 in A_6, but this can't be equal to the number of subgroups (i found two subgroups...
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