The length of life of a certain brand of light bulb is normally distributed with a mean of 1,000h and a standard deviation of 200h (note: this is a very unreliable set of light bulbs!). If I buy new light bulbs for two lamps before I leave for a month-long vacation (30 days), and I leave both lamps on when I leave, what is the probability that at least one will be working when I return?
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 + ...
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Here given,
The length of life of a certain brand of light bulb is normally distributed with a mean of 1,000h and a standard deviation of 200h (note: this is a very unreliable set of light bulbs!). If I buy new light bulbs for two lamps before I leave for a month-long vacation (30 days),
Here use standard normal distribution first
Then binomial
Here 30 days = 30×24 = 720 hour
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