In: Statistics and Probability
Use this information to answer the following questions:
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Based on the data above, what is the z score for the age of 74? 3 pts |
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Work: |
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Based on the data you have and the z table, what percentageof people might start to show signs of dementia at or afterage 74? Note: DO NOT ROUND 3 pts |
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Answer: |
Given that the Mean is m =70 and standard score s = 5.0
a) At X = 74
The Z score is calculated as:
b) To calculate the percentage of people might start to show the sign of dementia at or after 74, means, P(X>=74) is computed using its standardized score Z = 0.8
so, P(X>=74) = P(Z>0.8) is computed using excel formula =1-NORM.S.DIST(0.8, TRUE) which results in P(X>=74) = 0.2119.
This can also be computed using the Z table as:
The table always gives the percentage value from the left so, the correct value for the area to the right of Z score is calculated by subtracting the percentage value with 1.
so, P(X>=74) = 1-0.7881 =2119.