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Angel earned a score of 174 on Exam A that had a mean of 150 and a standarddeviation of 40. He is about to take Exam B that has a mean of 550 and a standarddeviation of 40. How well must Angel score on Exam B in order to do equivalentlywell as he did on Exam A? Assume that scores on each exam are normally distributed.

Sagot :

We need to calculate first for the z-score of Angel on Exam A. The z-score can be computed using the equation:

[tex]z=\frac{x-\operatorname{mean}}{\text{standard deviation}}[/tex]

Given the mean, score (represented by x), and the standard deviation, Angel's z-score in exam A is computed as follows:

[tex]\begin{gathered} z=\frac{174-150}{40} \\ z=\frac{24}{40}=0.6 \end{gathered}[/tex]

We now derive an equation solving for x to compute the needed score of Angel on Exam B so that she has the same performance as Exam A.

[tex]\begin{gathered} x-\operatorname{mean}=z\cdot\text{standard deviation} \\ x=\operatorname{mean}+z\cdot\text{standard deviation} \end{gathered}[/tex]

Using the z score computed on Exam A plus the mean and standard deviation for Exam B, the minimum points Angel needed will be:

[tex]\begin{gathered} z=(550)+(0.6\cdot40) \\ z=550+24=574 \end{gathered}[/tex]

Therefore, Angel needs a score of 574 on exam B so that he can do equivalently as well as Exam A.

Answer: 574 points