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Statistics question #4!!?

Leukemia and blood cancer discussion.

Statistics question #4!!?

Postby taylan » Fri Nov 04, 2011 1:35 pm

The extract of a plant native to Taiwan has been tested as a possible treatment for Leukemia. One of the chemical compounds produced from the plant was analyzed for a particular collagen. The collagen amount was found to be normally distributed with a mean of 71 and standard deviation of 10 grams per mililiter (g/mm). Suppose that a plant is randomly selected and the collegan amount is measured.

a) What is the probability that the amount is greater than 68 g/mm?

b) What is the probability that the amount is less than 79 g/mm?

c) What percentage plants have a collegan amount within 1 standard deviations of the mean?
taylan
 
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Statistics question #4!!?

Postby doctor » Fri Nov 04, 2011 1:36 pm

z = (X-Mean)/S.D
a) z value corresponding to X=68 is
z = (68-71)/10 = - 0.3
Required probability = Area under the standard normal curve right to z = - 0.3
= 0.1179+0.5000
= 0.6179 or 61.79%
b) z value corresponding to X=79 is
z = (79-71)/10 = + 0.8
Required probability = Area under the standard normal curve left to z = + 0.8
= 0.5000+0.2881
= 0.7881 or 78.81%
c) Mean +/- 1 S.D covers 68.26% of the items or
as per the empirical rule 68%
Therefore it can be said that 68% of the plants have a collagen amount
doctor
 
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