The soccer balls manufactured at a factory have pressures that are Normally distributed, with a mean pressure of 8.7 PSI and a standard deviation of 0.2 PSI. What percentage of soccer balls from the factory have a pressure between 8.1 and 8.7 PSI? 0.3% 49.85% 50% 99.7%

Respuesta :

Answer:

49.85 is right

Step-by-step explanation:

Using the Empirical Rule, it is found that:

49.85% of soccer balls from the factory have a pressure between 8.1 and 8.7 PSI.

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The Empirical Rule states that, in a normal distribution:

  • The middle 68% of the measures are within 1 standard deviation of the mean.
  • Following the same logic, 95% is within 2 standard deviations of the mean, and 99.7% within 3.

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  • In this question, the mean is of 8.7 PSI and the standard deviation is of 0.2 PSI.
  • 8.1 = 8.7 - 3(0.2), thus, 8.1 is 3 standard deviations below the mean.
  • The normal distribution is symmetric, which means that 50% of the measures are above the mean and 50% are below.
  • 99.7% of the 50% of the measures below the mean are between 8.1 and 8.7 PSI, thus, the percentage is:

[tex]P = 0.997(50) = 49.85\%[/tex]

49.85% of soccer balls from the factory have a pressure between 8.1 and 8.7 PSI.

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