\( X \) is a normally distributed random variable with mean 54 and standard deviation 13 . What is the probability that \( X \) is less than 25 ? Write your answer as a decimal rounded to the nearest thousandth.
Solución de tutoría real
Responder
Solución
Revisado y aprobado por el equipo de tutoría de UpStudy
Extra Insights
To find the probability that \( X \) is less than 25 for a normally distributed random variable \( X \) with mean \( \mu = 54 \) and standard deviation \( \sigma = 13 \), we first calculate the z-score using the formula: \[ z = \frac{X - \mu}{\sigma} \] Substituting the values: \[ z = \frac{25 - 54}{13} = \frac{-29}{13} \approx -2.2308 \] Now, we can look up this z-score in the standard normal distribution table (or use a calculator), which gives us the probability \( P(Z < -2.2308) \). Looking up \( z = -2.23 \) in the standard normal table, we find that the probability is approximately 0.0116. Thus, rounding to the nearest thousandth, the probability that \( X \) is less than 25 is: \[ \boxed{0.012} \]