1.Scores of an IQ test have a bell-shaped distribution with a mean of 100 and a
ID: 3180434 • Letter: 1
Question
1.Scores of an IQ test have a bell-shaped distribution with a mean of 100 and a standard deviation of 15. Use the empirical rule to determine the following.
(a) What percentage of people has an IQ score between 70 and 130?
(b) What percentage of people has an IQ score less than 85 or greater than 115?
(c) What percentage of people has an IQ score greater than145?
(a)_____ %
(Type an integer or a decimal.)
(b) __________%
(Type an integer or a decimal.)
(c) _________%
(Type an integer or a decimal.)
2. The following data represent the annual number of days over 100° F in a city
from 1905 to 2004. Approximate the mean and standard deviation of annual number of days over 100° F Treat the data as a population.
Number of
over 100 degrees Upper Fover 100° F days
0-9
10-19
20-29
30-39
40-49
50-59
60-69
Number of years
33
34
17
10
3
2
1
equals=
(Round to two decimal places as needed.)
sigmaequals=
(Round to two decimal places as needed.)
3. Charlene and Gary want to make trail mix. In order to get the right balance of ingridients for their tastes they bought 4 pounds of raisins at $3.13 per pound, 5 pounds of peanuts for $2.63, and 5 pounds of chocolate chips for $4.44 per pound.
Detemine the cost per pound of the trail mix?
The cost per pound of the trail mixtrail mix is
$.
(Round to the nearest cent.)
Number of
over 100 degrees Upper Fover 100° F days
0-9
10-19
20-29
30-39
40-49
50-59
60-69
Number of years
33
34
17
10
3
2
1
Explanation / Answer
1. According to 68–95–99.7 thumb rule, 68.27%, 95.45% and 99.73% of the values lie within one, two and three standard deviation from mean
a) Percentage of people has an IQ score between 70 and 130 = 95.45
(because 70 - 130 is within 2 standard deviations from mean)
b) Percentage of people has an IQ score less than 85 or greater than 115
= 100 - Percentage of people has an IQ score between 85 and 115
= 100 - 68.27
= 31.73
c) Percentage of people has an IQ score between 55 and 145 = 99.73
Percentage of people has an IQ score between 100 than145 = 99.73/2 = 49.865
Percentage of people has an IQ score less than 145 = 49.865 + 50 = 99.865
(Please post different questions separately)
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