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Use technology or a z-distribution table to find the indicated area.

The scores on a standardized exam are normally distributed with a mean of 400 and a standard deviation of 50.

Approximately 40% of the scores are greater than which score?

 

  • 370
  • 387
  • 413
  • 430
adore.nuk  Feb 28, 2018
 #1
avatar+88902 
+2

Don't know much about this, but here's my best shot

 

On the z score table, 40%  corresponds roughly with a z-score of about .25

 

So...we can solve this

 

z score  =   score  - mean

                  ____________

                    std deviation

 

.25  =  score - 400

          __________            multiply both sides by 50

               50 

 

50 (.25)  =  score  - 400     add 400 to both sides

 

50 (.25) + 400   =  score

 

412.5  =  score  ≈   413

 

 

cool cool cool

CPhill  Feb 28, 2018
edited by CPhill  Feb 28, 2018

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