\( X \) is a normally distributed random variable with mean 27 and standard deviation 13 . What is the probability that \( X \) is between 19 and \( 69 ? \) Write your answer as a decimal rounded to the nearest thousandth.
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To find the probability that \( X \) is between 19 and 69 for a normally distributed variable with a mean of 27 and a standard deviation of 13, we can use the Z-score formula: \[ Z = \frac{(X - \mu)}{\sigma} \] 1. For \( X = 19 \): \[ Z_1 = \frac{(19 - 27)}{13} = \frac{-8}{13} \approx -0.615 \] 2. For \( X = 69 \): \[ Z_2 = \frac{(69 - 27)}{13} = \frac{42}{13} \approx 3.231 \] Next, we can use the standard normal distribution table (Z-table) or a calculator to find the probabilities corresponding to these Z-scores. - The probability for \( Z_1 \approx -0.615 \) is approximately 0.268. - The probability for \( Z_2 \approx 3.231 \) is approximately 0.999. Now, to find the probability that \( X \) is between 19 and 69, we subtract the lower probability from the upper probability: \[ P(19 < X < 69) = P(Z < 3.231) - P(Z < -0.615) \approx 0.999 - 0.268 = 0.731 \] So, the probability that \( X \) is between 19 and 69 is approximately \( 0.731 \) when rounded to the nearest thousandth.