Exam 5: Normal Distributions

"IQ scores based on the Wechsler Adult Intelligence Scale are assumed to be normally distributed with a mean of 100 and a standard deviation of 15." What percentage of adults have IQ scores less than 90?

What percentage of z-scores in the standard normal distribution are less than z = 1.45?

What percentage of z-scores in the standard normal distribution are greater than z = -2.00?

"A recent study of Greek children estimated that the average weight of a 10-year old boy was 81.57 pounds with a standard deviation of 17.41 pounds (Papadimitriou et al., 2006)." What percentage of boys weigh between 70 and 90 pounds?

The shaded area in this distribution most closely represents ______.

About ______ of z-scores in the standard normal distribution are within ±1 standard deviations of the mean.

What percentage of z-scores in the standard normal distribution are between z = -.25 and z = .15?

Figure A is an example of a ______ distribution; Figure B is an example of a ______ distribution. Figure A Figure B

"The records of the National Weather Service indicate that, on the average, the city of San Jose receives 14.03 inches of rain each year, with a standard deviation of 5.19 inches." In what percentage of years would you expect there to be less than 12 inches of rain?

In the standard normal distribution, the mean is equal to 0 and the standard deviation is equal to 1.

The ______ of a normal distribution is equal to ______.

"Your score is almost two standard deviations above the mean." Which of the following statements is MOST accurate?

One of the characteristics of a normal distribution is that it ______.

The shaded areas in this distribution most closely represents ______.

"According to the National Center for Health Statistics, in 2005 the average birthweight of a newborn baby was approximately normally distributed with a mean of 119 ounces (7 lb, 7 oz) and a standard deviation of 19 ounces." What percentage of babies weighed more than 128 ounces (8 lb) at birth?

In which of the following ways is the standard normal distribution similar to other normal distributions?

If a variable is normally distributed with a mean of 30 and a standard deviation of 6, approximately ______ of the scores are between ______and ______.

Roughly all of the z-scores in the standard normal distribution are with in ______ standard deviations of the mean.

Normal distributions are an important concept to researchers because they ______.

What z-score designates or marks the bottom 20% of the standard normal distribution?