From a set of 1000 observations known to be normally distributed, the mean is 534 cm and SD is 13.5 cm. How many observations are likely to exceed 561 cm? How many will be between 520.5 cm and 547.5 cm? Between what limits will the middle 50% of the observations lie?

Question

From a set of 1000 observations known to be normally distributed, the mean is 534 cm and SD is 13.5 cm.  How many observations are likely to exceed 561 cm? How many will be between 520.5 cm and 547.5 cm? Between what limits will the middle 50% of the observations lie?

drwls · Answer

Try using the normal distribution tool at http://psych.colorado.edu/~mcclella/java/normal/accurateNormal.html

You should get 2.3% of 1000 or 23 for the first question. The range is 2 or more standard deviations frm the mean.
Between 520.5 and 547.5, with is + or - 1 one standard deviation, you will get 68.3% of the samples or 683 (on average). Actual results will vary statistically.

The middle 50% are between 524 and 543

vanessa · Answer

3/8 into a decimal