At a college the scores on the chemistry final exam are approximately normally distributed, with a mean of 75 and a standard deviation of 12. The scores on the calculus final are also approximately normally distributed, with a mean of 80 and a standard deviation of 8. A student scored 81 on the chemistry final and 84 on the calculus final. Relative to the students in each respective class, in which subject did this student do better?

Respuesta :

Answer:Calculus

Step-by-step explanation:

Given

Chemistry score are normally distributed with a mean score of 75 and standard deviation 12

[tex]\mu _1=75[/tex]

[tex]\sigma _1=12[/tex]

Calculus score

[tex]\mu _2=80[/tex]

[tex]\sigma _2=8[/tex]

For chemistry

[tex]z=\frac{81-75}{12}=0.4167\approx 0.42[/tex]

For calculus

[tex]z=\frac{84-80}{8}=0.5[/tex]

From Z score it is clear that student score better marks in calculus.

Using z-scores, it is found that due to equal z-scores, the student performed the same relative to the classes in each subject.

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Z-score:

  • In a set 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]

  • The Z-score measures how many standard deviations the measure is from the mean.
  • Relative to the respective class, the student did better in the discipline in which his grade had a higher z-score.

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Chemistry:

  • Mean of 75 means that [tex]\mu = 75[/tex]
  • Standard deviation of 12 means that [tex]\sigma = 12[/tex]
  • Grade of 81 means that [tex]X = 81[/tex]

The z-score is:

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

[tex]Z = \frac{81 - 75}{12}[/tex]

[tex]Z = 0.5[/tex]

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Calculus:

  • Mean of 80 means that [tex]\mu = 80[/tex]
  • Standard deviation of 8 means that [tex]\sigma = 8[/tex]
  • Grade of 84 means that [tex]X = 84[/tex]

The z-score is:

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

[tex]Z = \frac{84 - 80}{8}[/tex]

[tex]Z = 0.5[/tex]

Due to equal z-scores, the student performed the same relative to the classes in each subject.

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