A manufacturer knows that their items have a normally distributed lifespan, with a mean of 2.2 years, and standard deviation of 0.6 years. If you randomly purchase one item, what is the probability it will last longer than 3 years? Round answer to three decimal places
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To find the probability that a randomly purchased item will last longer than 3 years, we can use the Z-score formula: Z = (X - μ) / σ, where X is the value of interest (3 years), μ is the mean (2.2 years), and σ is the standard deviation (0.6 years). Plugging in the values: Z = (3 - 2.2) / 0.6 = 1.3333 (approximately). Next, we look up this Z-score in the standard normal distribution table or use a calculator. The area to the left of Z = 1.3333 is approximately 0.9099. To find the area to the right (the probability of lasting longer than 3 years), we subtract this value from 1: P(X > 3) = 1 - 0.9099 ≈ 0.0901. Therefore, the probability that the item will last longer than 3 years is approximately 0.090 (rounded to three decimal places).