72) Find the z-score for the value 55, when the mean is 58 and the standard devi

Question

72) Find the z-score for the value 55, when the mean is 58 and the standard deviation is 3. A) z =-1.33 B) z =-1.00 C) z 0.90 D) z =-0.90 73) Test scores for a history class had a mean of 79 with a standard deviation of 4.5. Test scores for a physics lass had a mean of 69 with a standard deviation of 3.7. Suppose a student gets a 83 on the history test and a 84 on the physics test. Calculate the z-score for each test. On which test did the student perform better? 74) The birth weights for twins are normally distributed with a mean of 2353 grams and a standard deviation of 647 grams. Use z-scores to determine which birth weight could be considered unusual. A) 3647 g B) 1200 g C) 2353 g D) 2000 g

Explanation / Answer

a)the z score when X=55 Z=55-58/3=-1 b)the test score for history test is 83 there fore the z score is Z=83-79/4.5=0.88 The test score for physics is 84 Z=84-69/3.7=4.05 since z score for physics test is greater the student performs better in it.

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