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Statistical question bugging me (has math in it)
Xeno
Registered User regular
Registered User regular
50. In a large study of the growth of children the following results were obtained:
For boys aged 12: average height=58.5 inches, SD height=2.5 inches
For boys aged 14: average height=63.5 inches, SD height=2.8 inches
About what percent of the 12-year-old boys in the study were taller than the average height of the 14-year-old boys?
a. 5%
b. 2%
c. 0%
d. 2.5%
e. 8%
Apparently the right answer is 2.5%. S.D. stands for standard deviation. Can someone help me out? Thanks a lot! It will really help me!
For boys aged 12: average height=58.5 inches, SD height=2.5 inches
For boys aged 14: average height=63.5 inches, SD height=2.8 inches
About what percent of the 12-year-old boys in the study were taller than the average height of the 14-year-old boys?
a. 5%
b. 2%
c. 0%
d. 2.5%
e. 8%
Apparently the right answer is 2.5%. S.D. stands for standard deviation. Can someone help me out? Thanks a lot! It will really help me!
Xeno on
0
Posts
The mean value +/- 2 times the standard deviation has roughly 95% of the data. That leaves 2.5% in either direction up or down.
Edit: I should add, this is assuming a reasonably bell shaped curve.
For linkage, see here. Look at "Interpreting the standard deviation."