Name_________________________ Sec__________ ID__________

STANDARD DEVIATION: CONCEPTS

RIDDLE: What's the main problem with the "rat race?"

_____1. The SD is more descriptive of a normal distribution than it is of a skewed distribution. (EVEN)

_____2. A normal distribution is symmetrical. (IF)

_____3. The square root of the SD is called the variance. (BUSINESS)

_____4. In a normal distribution, about 68% of the cases lie between the mean and one SD above the mean.

(TRAP)

_____5. In a normal distribution, about 95% of the cases fall within one SD of the mean. (WEALTH)

_____6. If two groups are being compared, the group with the larger SD has more variability. (YOU)

_____7. If M = 50.0 and SD = 10.0, about 34% of the cases in a normal distribution lie between the scores of

40 and 50. (WIN)

_____8. If M = 32.0 and SD = 5.0, about 34% of the cases in a normal distribution lie between the scores of 27

and 32. (YOU'RE)

_____9. If M = 100.0 and SD = 15.0, about 68% of the cases in a normal distribution lie between 66 and 134.

(QUICKLY)

_____10. If M = 500 and SD = 100, about 68% of the cases in a normal distribution lie between 400 and 600.

(STILL)

_____11. The SD was designed to describe skewed distributions. (LOST)

_____12. Three SD units on both sides of the mean includes over 99% of the area in a normal distribution. (A)

_____13. The SD is usually associated with the mean. That is, if the mean is used to describe the average, the

SD is usually used to describe the variability. (RAT)

Write the answer to the riddle here, putting one word on each line.

_________ ________ ________ ________, __________ __________ _________ _________.