A certain brand of lightbulb is advertised to last for 6500 hours. The life-span of a randomly selected bulb is normally distributed with a mean of 6600 hours and a standard deviation of 200 hours. What is the probability that a bulb lasts longer than its advertised life-span?

69.15% probability that a bulb lasts longer than its advertised life-span

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean and standard deviation , the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

What is the probability that a bulb lasts longer than its advertised life-span?

Advertised to last 6500 hours, so this probability is 1 subtracted by the pvalue of Z when X = 6500.

has a pvalue of 0.3085.

1 - 0.3085 = 0.6915

69.15% probability that a bulb lasts longer than its advertised life-span

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step-by-step explanation:

a line is an defined derm because it

a)contains an infinite number of points b) can be used to create other geometric shapes c)describes something that does not have width or depth d) is a term that does not have a formal definition. a line is an undefined term because it: contains an infinite number of points.