# distribution

• Sep 19th 2006, 02:50 AM
bennyya
distribution
Hiya!

I need some help with these questions. I'm unsure where to start...

1. Given that z is the standard normal random variable, find P(z > -1.62).

2. Given a sample of ten numbers from 0 to 9 then the coefficient of variation for the same sample of 10 numbers is what?

3. Y is a normally distributed random variable with mean 10 and standard deviation 4. Find the probabilty that Y is greater than 11.

4. P(z >= c) = 0.8980, find c.

5. Carpet manufacturer has a variety of carpet with an average of 1.5 flaws per square metre. These flaws are random and independent. Find the probabilty of fewer than two flaws in a random chosen square metre of carpet.

Thanks!
• Sep 19th 2006, 05:32 AM
Glaysher
Quote:

Originally Posted by bennyya
Hiya!

I need some help with these questions. I'm unsure where to start...

1. Given that z is the standard normal random variable, find P(z > -1.62).

2. Given a sample of ten numbers from 0 to 9 then the coefficient of variation for the same sample of 10 numbers is what?

3. Y is a normally distributed random variable with mean 10 and standard deviation 4. Find the probabilty that Y is greater than 11.

4. P(z >= c) = 0.8980, find c.

5. Carpet manufacturer has a variety of carpet with an average of 1.5 flaws per square metre. These flaws are random and independent. Find the probabilty of fewer than two flaws in a random chosen square metre of carpet.

Thanks!

1. P(Z > -1.62) = P(Z < 1.62) by symmetry

Look up 1.62 in your copy of the standard normal distrbution table

2. Not sure what you mean

3. Y~N(10, 4^2)

P(Y > 11) = P(Z > (11 - 10)/4) = P(Z > 0.25) = 1 - P(Z < 0.25)

Look up 0.25 in your table and stick it in the calculation

4. P(Z > c) = 0.8980
P(Z < -c) = 0.8980

Look up the z value for 0.8980 in your table. Multiply it by -1 to find c

5. X~Po(1.5)

P(X < 2) = P(X = 0) + P(X = 1)

Work out the probabilities individually and add them together using the formula for a Poisson distbution