Statistics and Probability Answers

a company that manufactures rivets believes the shear strength of the rivets they manufacture follows a normal model with a mean breaking strength of 950 pounds and a standard deviation of 40 pounds

a) what percentage of rivets selected at random will break when tested under a 900 pound load?
b) you're trying to improve the rivets and want to examine some that fail. use a simulation to estimate how many rivets you might need to test in order to find three that fail at 900 pounds or below.

Over the last 10​ years, the average number of deaths due to accidents involving a certain commercial airline has been about 29 per year. Over the same​ period, the average number of passengers of the airline has been more than 4.8 million per year. Estimate the probability of dying on a particular flight

Suppose that 61.5% of brides are younger than their grooms. Suppose one were to consider simple random samples of size 40 of brides.
What is the probability that the proportion of brides in a sample of size 40 who are younger than their grooms exceeds 0.625?

Examine each of the following questions for possible bias. if you think the question is biased indicate how and purpose a better question:

a) should companies that pollute the environment be compelled to pay the costs of cleanup?
b) given that 18 year olds are old enough to vote and serve in the military is it fair to set the drinking age at 21?

An amusement park has opened a new roller coaster. it is so popular that people are waiting up to 3 hours for a 2 minute ride. concerned about how patrons ( who paid a large amount to enter the park and ride on the rides) feel about this they survey every 10th person on the line for the roller coaster starting from a randomly selected individual.

a) what kind of sample is this?
b) what is the sampling frame?
c) is it likely to be representative ?
d) what members of the population are likely to be omitted?

A company packaging snack food maintains quality control by randomly selecting 10 cases from each days production and weighing the bags. Then they open one bag from each case and inspect the contents

a)population
b)parameter
c)sampling frame
d)sample
e)method
f)left out
g)bias

A question posted on the gamefaqs.com website on Aug. 1, 2011 asked visitors to the site " do you have a social life outside the internet?" 22% of 55,58 said "no" or "not really, most of my personal contact is online"

a) population
b)parameter
c)sampling frame
d) sample
e)method
f)left out
g)bias

There is a sample of 200 contained of
50 freshman
50 sophomores
50 juniors
50 seniors

a) do you think the group was using SRS? Why
b) What sampling design do you think they used?

The probabilities of a boy passing English and Mathematics tests are a and b respectively. Find the probability of the boy failing both tests.

10 red marbles and 10 blue marbles are placed into a bag. Alex mixes up the bag and randomly selects a marble. He continues to do so, replacing the marble after each selection, until a red marble is selected.
a. What is the probability that the first time that a red marble is pulled is on Alex’s 6th try?
b. On average, how many marbles will Alex have to pull in order to get a red marble? (Hint: use math expectation)