# 2 more math questions

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

1. ### ATLATLATL

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

3. ### gochi

Joined:
Nov 24, 2006
Messages:
1,105
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 cowgoesmoo fan!

Joined:
Dec 13, 2005
Messages:
684
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 Ultra Senior Member Dentist

Joined:
Oct 25, 2006
Messages:
1,801
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.

Joined:
Oct 25, 2006
Messages:
1,801
5
Status:
Dentist