sampling distribution

As the sample size n increases without limit, the shape of the distribution of the sample means taken with replacement from a population with mean μ and standard deviation σ will approach a normal distribution. This distribution will have m..

The mean weight of girls in grade 12 of school X is 125 pounds, and the standard deviation is 20 pounds. If a sample of 25 girls is selected, then what is the probability that the mean of the sample will be greater than 128 pounds? Assume the variable is normally distribute..

A sample of 30 RAM chips was tested for the average access time. The standard deviation was found to be 2 nanosec. Find the 90% confidence interval for the true standard deviation. Assume that the variable is normally distributed. => between 1.7 and 2.6 or between 1.6 and 2.5 or..

Random Variables and Probability Distributions - It is often very important to allocate a numerical value to an outcome of a random experiment. For example, consider an experiment of tossing a coin twice and note the number of heads (x) obtained. Outcome HH HT TH TT No. of heads (x) 2 1 1..

Maxwell's Speed Distribution Law - The rms speed of an oxygen molecule in a sample at 300 K is about 480m/s. This does not mean that the speed of each molecule is 480 m/s. Many of the molecules have speed less than 480m/s and many have speed more than 480m/s. Maxwell derived an ..

If is often very important to allocate a numerical value to an outcome of a random experiment. For example consider an experiment of tossing a coin twice and note the number of heads (x) obtained. Outcome : HH HT TH TT No. of heads (x) : 2 1 1 0 x is called a random variable, which can assume the v..

Let S be a sample space associated with a given random experiment. A real valued function X which assigns to each w i S, a unique real number, X( w i ) = x i is called a random variable . Two types of random variables are 1. Continuous random variable, 2. discrete ra..

Assume that the weights of 3,000 students at a university are normally distributed with mean 150 pounds and a standard deviation of 7 pounds. If 100 samples of 30 students each are obtained, then what would be the expected mean and standard deviation? => 150 lbs, 7 10 lbs or 150..

Assume that the weights of 3,000 students at a university are normally distributed with mean 150 pounds and a standard deviation of 2.72 pounds. How many samples would you expect to find the mean between 147 and 155 pounds? => 83 or 82 or 84 or 81..

An ice cream manufacturer sells ice-creams in 3 sizes : large, normal and small packs in the ratio 3 : 5 : 2. The company distributes free samples of a new flavor in 250 large, 400 normal and 350 small packs as a trial. The company is interested to know and change accordingly th..