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?
Features Features Normal distribution is characterized by two parameters, mean (µ) and standard deviation (σ). When graphed, the mean represents the center of the bell curve and the graph is perfectly symmetric about the center. The mean, median, and mode are all equal for a normal distribution. The standard deviation measures the data's spread from the center. The higher the standard deviation, the more the data is spread out and the flatter the bell curve looks. Variance is another commonly used measure of the spread of the distribution and is equal to the square of the standard deviation.
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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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