1. For infant girls, the mean body length at 10 months is 72 centimeters with a standard deviation of 3 centimeters. The 75th percentile for a 10 month-old girl is ____ centimeters? (Round to one decimal place)

Respuesta :

Using the normal distribution, the 75th percentile for a 10 month-old girl is 74 centimeters.

Normal Probability Distribution

The z-score of a measure X of a normally distributed variable with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex] is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

  • The z-score measures how many standard deviations the measure is above or below the mean.
  • Looking at the z-score table, the p-value associated with this z-score is found, which is the percentile of X.

The mean and the standard deviation are given, respectively, by:

[tex]\mu = 72, \sigma = 3[/tex]

The 75th percentile is X when Z = 0.675, hence:

0.675 = (X - 72)/3

X - 72 = 3 x 0.675

X = 74.

The 75th percentile for a 10 month-old girl is 74 centimeters.

More can be learned about the normal distribution at https://brainly.com/question/15181104

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