ch3 day2
SAT scores are normallydistributed with mean 500 and standard deviation 100. Jason scores 440 on the math SAT. Jason's standard score is
-0.6
The 62nd percentile of a standard Normal distribution is apporximately
0.31
The height of the horizontal line (that is, the density curve) is
1/60
The histogram of several hundred observations shows a Normal distribution shape. The smallest observation is 11 and the largest is 89. We can estimate that the standard deviation of this distribution is approximately
13
Scores on the ACT college entrance exam follow the Normal distribution with mean 18 and standard deviation 6. Wayne's standard scoreon the ACT was -0.7. What was Wayne's actual ACT score?
13.8
About what percent of the cockroaches have weights less than 78 grams
16%
From this Normal curve, we see that the mean heart disease death rate per 100,000 people is about
190
Scores on the GRE follow a Normal distribution. Jennifer's score is 2 standard deviations above the mean. About what percent of scores are higher than Jennifer's?
2.5%
90% of the time, the alarm went off within__ seconds of the time it was set for.
27
Entomologist Heinz Kaefer has a colony of bongo spiders in his lab. There are 1000 adult spiders in the colony. mean 11 grams and standard deviation 2 grams. About how many spiders in the colony weigh more than 12 grams?
310
If the heights of 99.7% of American men are between 5'0 and 7'0, what is your estimate of the standard deviation of the height of American men?
4 inches
IQs among undergraduates at Mountain Tech are approximately Normally distributed. Mean = 110. 95% have IQs 100-120. The standard deviations of these IQs is about
5
Suppose we call an IQ of 110 normal. What percent of the population have "below normal" IQs?
50%
The heights of American menaged 18 to 24 are Normally distributed with mean 68 inches and standard deviation 2.5 inches. About 95% of all young men have heights between
63 inches and 73 inches
From the normal curve, we see that the standard deviation of the heart disease rate per 100,000 people is closest to
65
The heights of American men aged 18 to 24 are Normally distributed with mean 68 inches and standard deviation 2.5 inches. So half of all young men are taller than
68 inches
Point A on this Normal curve corresponds to
74 grams
Point C on this Normal curve corresponds to
78 grams
What range of IQ scores contain the central 95% of the population?
80 to 140
About what percent of the cockroaches have weights between 76 grams and 84 grams?
95%
Five of the seven points marked on this density curve make up the five-number summary for this distribution. Which two parts are not part of the five-number summary?
B and F
At which point on the Normal curve is the median of the distribution of cockroach weights located?
D
About what percent of the adult population have an IQ lower than 80?
None of the above
The standard deviation of this Normal distribution is
about 10
The mean of this Normal distribution is
about 50
Which of these distributions is least likely to be Normally distributed?
annual salaries of all professors at your college
The third quartile of the distribution of IQ scores is
between 110 and 125
Suppose the data reported deaths per 1,000 people instead of deaths per 100,000 people. The mean death rate in the previous question would be
divided by 100
Wayne's buddy Garth took the SAT. His standard score on the SAT was 0.3. This means that Garth's actual score was
less than 1 standard deviation above the mean SAT score
What percentage of times did the alram go off within 10 seconds of the time it was set for?
33%
The figure above is the density curve of a distribution. This distribution is
skewed to the left
Since IQs scores are Normally distributed with mean 110 and standard deviation 15, then about 40% of the scores are between
the 30th and 70th percentiles
