\( X \) is a normally distributed random variable with mean 62 and standard deviation 10 . What is the probability that \( X \) is between 32 and 72 ? Use the \( 0.68-0.95-0.997 \) rule and write your answer as a decimal. Round to the nearest thousandth if necessary.
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To find the probability that \( X \) is between 32 and 72 using the \( 0.68-0.95-0.997 \) rule, we start by calculating how many standard deviations these values are from the mean of 62. First, we find the z-scores: - For 32: \( z = \frac{32 - 62}{10} = -3 \) - For 72: \( z = \frac{72 - 62}{10} = 1 \) Now, we know from the empirical rule: - About 68% of the data is within 1 standard deviation (between 52 and 72), - About 95% is within 2 standard deviations (between 42 and 82), - About 99.7% is within 3 standard deviations (between 32 and 92). Since we're looking for the probability that \( X \) is between 32 (which is -3 standard deviations) and 72 (which is +1 standard deviation), we add the probabilities within those ranges. From -3 to +1 standard deviations, the probability is approximately: - The total area from -3 to +3 standard deviations is about 99.7%, and just from -3 to +1 will capture about 95% (total from -2 to +2) minus a bit, making it approximately 81.5%. Therefore, the probability that \( X \) is between 32 and 72 is approximately \( 0.815 \) when rounded to the nearest thousandth.