Bicycles arrive at a bike shop as parts in a box. Before they can be sold, they must be unpacked and assembled. Based on past experience, the bike shop owner knows that assembly times follow (roughly) a Normal distribution with a mean of 25 minutes and a standard deviation of 3 minutes. A customer walks into the bike shop and wishes to buy a bike like the one in the window, but in a different color. The shop has one, but it is still in the box, so it will need to be assembled. What is the probability that the bike will be ready within a half hour?

Definition Definition Measure of central tendency that is the average of a given data set. The mean value is evaluated as the quotient of the sum of all observations by the sample size. The mean, in contrast to a median, is affected by extreme values. Very large or very small values can distract the mean from the center of the data. Arithmetic mean: The most common type of mean is the arithmetic mean. It is evaluated using the formula: μ = 1 N ∑ i = 1 N x i Other types of means are the geometric mean, logarithmic mean, and harmonic mean. Geometric mean: The nth root of the product of n observations from a data set is defined as the geometric mean of the set: G = x 1 x 2 ... x n n Logarithmic mean: The difference of the natural logarithms of the two numbers, divided by the difference between the numbers is the logarithmic mean of the two numbers. The logarithmic mean is used particularly in heat transfer and mass transfer. ln x 2 − ln x 1 x 2 − x 1 Harmonic mean: The inverse of the arithmetic mean of the inverses of all the numbers in a data set is the harmonic mean of the data. 1 1 x 1 + 1 x 2 + ...