Download 7.3 and 7.4 Extra Practice

7.3 and 7.4
Extra Practice
7.3-7.4 Quiz: TOMORROW
Section 7.3
•
Find the mean, median, and mode of the
data set
1. 12, 15, 17, 11, 8, 14, 7, 14
x = 12.25, Median = 13, Mode = 14
2. 0.3, 8.9, 7.6, 3.7, 1.5, 4.2, 7.6, 8.1
x = 5.2375, Median = 5.9, Mode = 7.6
Section 7.3
•
Find the range and standard deviation of
the data set.
1. 1.25, 3.69, 5.67, 4.89, 0.12, 4.35, 2.78
Range = 5.55, Standard Deviation = about 1.8
2. 515, 720, 635, 895, 585, 690, 770, 840
Range = 380, Standard Deviation = about 119.6
Standard Deviation
xi – x
( x i – x )2
Sum:
sum

n

Section 7.4
•
A normal distribution has a mean x and standard
deviation σ. Find the indicated probability for a
randomly selected x-value from the distribution.
1. P(x < x + 2σ)
97.5%
2. P(x > x – σ)
84%
3. P( x - 3σ < x < x +σ)
83.85%
Section 7.4
•
Give the percent of the area under the
normal curve represented by the shaded
region.
2.5%
50%
Section 7.4
•
A normal distribution has a mean of 63.7 and a
standard deviation of 2.9. Find the probability that
a randomly selected x-value from the distribution
is in the given interval.
1. Between 57.9 and 66.6
81.5%
2. At most 69.5
97.5%
Section 7.4
•
A normal distribution has a mean of 496 and a
standard deviation of 109. Use the standard
normal table on p. 296 to find the indicated
probability for a randomly selected x-value from
the distribution.
1. P(x < 630)
.8849 88.49%
2. P(x < 270)
.0179 1.79%