Originally posted by w.h.o

that makes sense. It's an online hw though, so it's very picky about the answers. Are you good at using the table, I'm still confused.

Originally posted by Dephira

Type:

=NORM.DIST(457, 487, 7, TRUE)

into a cell in excel

Originally posted by jackieshann

yes im good at maths but i wont help you because im lazy/

Originally posted by - JED -

You have to search the P of the z you calculate in the B column of the normal distribution table.

Originally posted by w.h.o

The amount of fill in a half-liter (500 ml) soft drink bottle is normally distributed. The process has a standard deviation of 3.5 ml. The mean is adjustable.

(a)
Where should the mean be set to ensure a 95 percent probability that a half-liter bottle will not be underfilled? (Round your answer to 2 decimal places.)

Mean ml

(b)
Where should the mean be set to ensure a 99 percent probability that a half-liter bottle will not be underfilled? (Round your answer to 2 decimal places.)

Mean ml

(c)
Where should the mean be set to ensure a 99.9 percent probability that a half-liter bottle will not be underfilled? (Round your answer to 2 decimal places.)

Mean ml

Originally posted by Dephira

I'll help with a), the rest should be easy then:

This time you don't know the mean, so you'll have: (x-500)/3.5 in order to standardize it. You also want a z-score such that the left side of your probability is 95%, typically you'd use 1.64 so that. You can also look it up in the table, by simply looking for the p-value that gives you a p of 0.95 (usually you won't find the exact probability, so you have to find the closest one). So now you just set (x-500)/3.5 equal to 1.64, and solve for x.

Originally posted by Dephira

I'll help with a), the rest should be easy then:

This time you don't know the mean, so you'll have: (x-500)/3.5 in order to standardize it. You also want a z-score such that the left side of your probability is 95%, typically you'd use 1.64 so that. You can also look it up in the table, by simply looking for the p-value that gives you a p of 0.95 (usually you won't find the exact probability, so you have to find the closest one). So now you just set (x-500)/3.5 equal to 1.64, and solve for x.

Originally posted by question 10

At a certain fire station, false alarms are received at a mean rate of 0.3 per day. In a year, what is the probability that fewer than 90 false alarms are received? Note: You may need to use Excel to calculate the exact probabilities if the z score is not in the book's tables. (Consider 365 days a year. Round the standard deviation to 3 decimal places, z score to 2 decimals and final answer to 4 decimal places.)

Originally posted by question 11

Automobile warranty claims for engine mount failure in a Troppo Malo 2000 SE are rare at a certain dealership, occurring at a mean rate of 0.12 claim per month.

(a)
What is the probability that the dealership will wait at least 7 months until the next claim? (Round your answer to 4 decimal places.)

Probability

(b)
What is the probability that the dealership will wait at least a year? (Round your answer to 4 decimal places.)

Probability

(c)
What is the probability that the dealership will wait at least 2 year? (Round your answer to 4 decimal places.)

Probability

(d)
What is the probability that the dealership will wait at least 7 months but not more than 1 year? (Round your answer to 4 decimal places.)

Probability:

Originally posted by question 35

The weight of a small Starbucks coffee is a normally distributed random variable with a mean of 310 grams and a standard deviation of 10 grams. Find the weight that corresponds to each event. (Use Excel or Appendix C for calculation of z-value. Round your final answers to 2 decimal places.)


a. Highest 10 percent GOT IT
b. Middle 50 percent ?? to ??
c. Highest 80 percent GOT IT
d. Lowest 10 percent GOT IT