for 2000 patients, blood-clotting time was normally distributed with a mean of 8 seconds and a standard….. ?
deviation of 3 seconds. what percent had blood-cloting times between 5 and 11 seconds?
a. 68%
b. 34%
c. 49/5%
d. 47/5%
This all boils down to the Standard Normal Distribution….
68% is your answer because for a Standard Normal Distribution approximately 68% of the values will fall within +/- one standard deviatio of the mean.
This is exactly what you have……
8 +/- one standard deviation ====> (8-3 , 8+3) ====> (5, 11)
It is good to also know the following
95% of values fall within 2 standard deviations from the mean
99.73% of values fall within 3 standard dev from the mean
October 31st, 2009 at 1:07 pm
It is 68%
In normal distribution, the area under the curve from mean+ – one s.d. is about 68%, mean + – 2 s.d. would be nearly 95% and mean + – 3 s.d. contains more than 99% of the values.
References :
October 31st, 2009 at 1:15 pm
This all boils down to the Standard Normal Distribution….
68% is your answer because for a Standard Normal Distribution approximately 68% of the values will fall within +/- one standard deviatio of the mean.
This is exactly what you have……
8 +/- one standard deviation ====> (8-3 , 8+3) ====> (5, 11)
It is good to also know the following
95% of values fall within 2 standard deviations from the mean
99.73% of values fall within 3 standard dev from the mean
References :