OpenStudy (anonymous):

The heights of 16-month-old oak seedlings are normally distributed with a mean of 31.5 cm and a standard deviation of 10 cm. What is the range of heights between which 75% of the seedlings will grow?

3 years ago
OpenStudy (tkhunny):

Bad Question: "will grow" is wrong. It's not a matter of opinion. It's wrong. It should be "are expected to grow". Bad Question: There is not a unique answer. "the range" is incorrect. Does it want it symmetrical about the mean? \((0,38.245)\) gives 75% \((11.546,38.988)\) gives 75% \((21.551,44.846)\) gives 75% \((19.997,43.003)\) gives 75% <== The symmetric one.

3 years ago
OpenStudy (anonymous):

It's right out of the textbook. The back of the book has the symmetric answer. How did you come up with that?

3 years ago
OpenStudy (tkhunny):

The question needs to be severely rewritten. |dw:1402364005469:dw| How many standard deviations from the mean will cut off 37.5% of the area?

3 years ago