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The Precision Scientific Instrument Company manufactures thermometers that are supposed to give readings of OC at the freezing point of water. Tests on a large sample of these thermometers reveal that at the freezing point of water, some give readings below 0°C (denoted by negative numbers) and some give readings above 0°C (denoted by positive numbers). Assume that the mean reading is 0°C and the standard deviation of the readings is 1.00°C. Also assume that the frequency distribution of errors closely resembles the normal distribution. A thermometer is randomly selected and tested. Find the temperature reading corresponding to the given information. Find Q3, the third quartile.
A) 0.53
B) 0.67
C) -1.3
D) 0.82

Respuesta :

Using the normal distribution, it is found that the third quartile is of Q3 = 0.67, hence option B is correct.

In a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:

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

  • It measures how many standard deviations the measure is from the mean.  
  • After finding the z-score, we look at the z-score table and find the p-value associated with this z-score, which is the percentile of X.

In this problem:

  • The mean is of 0ºC, hence [tex]\mu = 0[/tex].
  • The standard deviation is of 1ºC, hence [tex]\sigma = 1[/tex].

The third quartile is X when Z has a p-value of 0.75, as [tex]100\frac{3}{4} = 75[/tex], hence X when Z = 0.67.

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

[tex]0.67 = \frac{X - 0}{1}[/tex]

[tex]X = 0.67[/tex]

To learn more about the normal distribution, you can take a look at https://brainly.com/question/24663213

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