Question

The age at which babies walk is normally distributed with a mean of 13 months and a standard deviation of 1.5 months. Which age separates the oldest 25% that walked?

Answer 1

To find the age that separates the oldest 25% of babies who walk, we can use the z-score corresponding to the 75th percentile. By substituting the mean, standard deviation, and z-score into the formula, we find that the age is approximately 14.01 months.

Step-by-step explanation:

To find the age that separates the oldest 25% of babies who walk, we need to find the z-score corresponding to the 75th percentile and then use it to find the corresponding age. The z-score is found using the formula z = (x - μ) / σ, where x is the value, μ is the mean, and σ is the standard deviation. In this case, the mean is 13 months and the standard deviation is 1.5 months. The z-score that corresponds to the 75th percentile is approximately 0.674. To find the corresponding age, we use the formula z = (x - μ) / σ and solve for x. Rearranging the formula, we have x = μ + z * σ. Substituting the values, we get x = 13 + 0.674 * 1.5 = 14.01 months. Therefore, the age that separates the oldest 25% of babies who walk is approximately 14.01 months.