can any one explain biostatics ques - arya4

[ArchivalUser]

a study of 400 pts hospitalizes with DM related complications shows that serum cholesterol level is normally distributed variable with a mean of 220 mg/dl and standard deviation of 10mg/dl. Based on the study results how many pts do u expect to have serum cholesterol >240 mg/dl in this study?
a-2
b-10
c-20
d-64
e-128

[ArchivalUser]

is it bbb??

2 standard deviations above and below mean, include 95% of population total.. that 2.5% is below 2 standard deviations and 2.5% is above 2 standard deviations..

here >240 is more than 2 standard deviations above, so 2.5% of 400 is 10

[ArchivalUser]

a-2

[ArchivalUser]

yes the ans is b

[ArchivalUser]

i have a doubt about the Q " ARYA" is it above 240 or > or = 240...

mean = 210 standard deviation= 10 ......1 SD = 210+/-10 ( 68%)
.......................................> 2 SD= 210 +/- 2X (10) = 190-240 (95.5)
........................................> 3SD= 210 +/- 3 ( 10) 180-250 ( or up 240)= 99.7
( 0.15 patients are above/or below 2.40 or 99.7)

[ArchivalUser]

its >240 but there is a line below greater sign so i think its both greater and equal to

[ArchivalUser]

yep thanks arya for the correction...