1. Guest, be sure to check out How To Get Into Dental School, our free downloadable PDF with step-by-step details for dental school applicants!
    Dismiss Notice

2 more math questions

Discussion in 'DAT Discussions' started by ATLATLATL, May 2, 2007.

  1. ATLATLATL

    Joined:
    Jan 9, 2007
    Messages:
    113
    Likes Received:
    0
    Status:
    Pre-Dental
    if log2=A and log3=B then log six is?
    a+b
    a-b
    a*b
    a/b
    a^b

    answer is a+b
    i would've thought a*b

    oh and the other question is...

    with one fair die, find the probability of throwing two fours in five attempts?
     
  2. Thread continues after this sponsor message. SDN Members do not see this ad.

  3. gochi

    Joined:
    Nov 24, 2006
    Messages:
    1,105
    Likes Received:
    0

    I cant really explain this, but I know how it works, so let me illustrate.

    Log X + Log Y= Log(XY) likewise Log X - Log Y= Log(X/Y)

    These are just properties of LOGARITHMS.

    Q: if log2=A and log3=B then log six is?

    A: log 6= log2 + log3=log(2*3)=log6 which is the same as a=3;b=3--> ab.
     
  4. Lonely Sol

    Lonely Sol cowgoesmoo fan!

    Joined:
    Dec 13, 2005
    Messages:
    684
    Likes Received:
    0
    Status:
    Pre-Dental


    Would this a binomial probablity because probability of sucess equals 1-probability oif failure. The reason is because there is only two choices; rolling a 4 or not rolling a 4:

    Since you have 1/6 chances of throwing 4 and 5/6 chance of throwing anything but 4.

    Since, you want 2 4s in 5 attenpts, you do the following:


    (1/6*1/6*5/6*5/6*5/6 )*10 (I got 10 from 5C2)

    *plz correct me if I am wrong
     
  5. Streetwolf

    Streetwolf Ultra Senior Member
    Dentist

    Joined:
    Oct 25, 2006
    Messages:
    1,801
    Likes Received:
    5
    Status:
    Dentist
    Want two 4s in 5 tries.

    5 choose 2 - picks the two throws that will be a 4.
    (1/6)^2 - odds of throwing two 4s.
    (5/6)^3 - odds of throwing three non-4s.

    10*(1/36)*(125/216) = 1250/7776 = (625/3888) = 0.16075

    So 16.075%.

    Correct, LS.
     
  6. Streetwolf

    Streetwolf Ultra Senior Member
    Dentist

    Joined:
    Oct 25, 2006
    Messages:
    1,801
    Likes Received:
    5
    Status:
    Dentist
    Start with: X * Y
    = 10^(Log X) * 10^(Log Y) <-- 10^(Log X) = Log(10^X) = X
    = 10^(Log X + Log Y) <-- A^X * A^Y = A^(X+Y)

    So we have XY = 10^(Log X + Log Y).
    Take the Log of both sides:

    Log(XY) = Log(10^(Log X + Log Y)
    Log(XY) = Log X + Log Y

    Try it for Log(X/Y).
     

Share This Page