Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 Help Me ! » Context-free grammar » 2008-08-11 08:18:13

Kenshinofkin
Replies: 1

Create a context-free grammar that generates the language a^nb^(n+m)c^m.

I came up with this so far:

S -> aAc
A -> bb

But this only does the case with abbc. Can anyone help with this one?

#2 Help Me ! » Probability questions (what formulas do I use) » 2008-08-03 13:17:42

Kenshinofkin
Replies: 1

Could someone help me with these problems. I am not sure what formulas to use. Thanks

A company produces component parts for an engine. Parts specifications suggest that 95% of items meet specifications. The parts are shipped to customers in lots of 100.

a) What is the probability that more than 2 items will be defective in a lot?
b) What is the probability that more than 10 items will be defective in a lot?

The turkeys found in a particular county have an average weight of 15.6 pounds with a standard deviation of 4.0 pounds. Forty-five turkeys are randomly selected for a county fair.

a) Find the probability that the average weight of the turkeys will be less than 14.5 pounds.
b) What is the probability that the average weight of the turkeys will be more than 17 pounds?
c) Find the probability that the average weight of the turkeys will be between 13 and 18 pounds.

#3 Help Me ! » Variance » 2008-08-01 05:58:53

Kenshinofkin
Replies: 1

A dealer's profit in units of $5,000 on a new automobile is a random variable X having density function

f(x,y) = 2(1-x) for -1 <= x <= 1
a) Find the vaiance in the dealer's profit.
b) Demonstrate that chebyshev's inequality holds for k = 2 with the density function above.
c) What is the probability that the profit exceeds $500?

a) E(2(1-x)) = -4
What is f(x) in this problem? is it just x?

= -1
b) How can I show that it holds true?
c) ???

#5 Re: Help Me ! » Probibility question » 2008-08-01 02:06:39

I am not sure I am using this right but here goes.

d) f(k;lamda) = (0^12 * e^-0) /12! = 0
e) f(k;lamda) = (1^12 * e^-1) /12! = .8 x 10^9
f) f(k;lamda) = (12^12 * e^-12) /12! = .1114

Did I do this right?

#6 Help Me ! » Probibility question » 2008-07-31 20:48:26

Kenshinofkin
Replies: 4

A pediatric nurse is studying the number of babies born at a hospital with congenial defects. Data shows that on the average, one baby with a congenial defect is born per month
a) What type of probability distribution is appropriate for this problem?
b) Find the expected number of babies born in one year with congenial defects.
c) Find the standard deviation of the number of babies born in one year with congenial defects.
d) Find the probability that no babies are born with congenial defects in one year.
e) Find the probability that at least one baby is born with congenial defects in a year.
f) Find the probability that exactly 12 babies are born with congenial defects in a year.

Only one I think I know is b) 12?

#7 Help Me ! » Regexp help » 2008-07-09 00:02:25

Kenshinofkin
Replies: 2

I my class we went over nonregular languages a little bit but not much at all. I understand that a*b* is not a regexp because there can be an infinite number of a's or b's but all of the following seem to me like they are regexps:

How can I fine if they are a regexp or not. They all seem to be.

Board footer

Powered by FluxBB