Name Directions Solve the following problems and answer the
Solution
Mean = u = 150
SD = 5
1)
z = (x - u) / SD
z = (145 - 150)/5 = -1
P(z < -1) = 0.1587
z = (x - u)/SD
z = (155-150)/5 = 1
P(z < 1) = 0.8413
So, P(-1 < z < 1) = 0.8413 - 0.1587
0.6826
68.26%
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2)
For x = 140, z = -2
P(z < -2) = 0.0228
For x = 160, z = 2
P(z < 2) = 0.9772
So, 0.9772 - 0.0228
0.9544
95.44%
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3)
For x = 135, z = -3
P(z < -3) = 0.0013
For x = 165, z = 3
P(z < 3) = 0.9987
0.9987 - 0.0013
0.9974
99.74%
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4)
x = 148
z = (x - u) / SD
z = (148 - 150)/5
z = -2/5
z = -0.4
Use this link ---> https://www.easycalculation.com/statistics/p-value-for-z-score.php
P(z > -0.4) = 0.6554 = 65.54% --> ANSWER
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5) P(x <= 148) = 1 - 0.6554
0.3446 = 34.46% --> ANSWER
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6) Between 147 and 157 :
z = (147 - 150) / 5 = -0.6
P(z < -0.6) = 0.2743
z = (157 - 150) / 5 = 1.4
P(z < 1.4) = 0.9192
0.9192 - 0.2743
0.6449
64.49% --> ANSWER
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7)
z = (141 - 150) / 5
z = -1.8
P(z < -1.8) = 0.0359
z = (149 - 150) / 5
z = -0.2
P(z < -0.2) = 0.4207
0.4207 - 0.0359
0.3848
38.48% --> ANSWER
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8)
z = (151 - 150)/5 = 0.2
P(z < 0.2) = 0.5793
z = (159 - 150)/5 = 1.8
P(z < 1.8) = 0.9641
0.9641 - 0.5793
0.3848
38.48%
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9)
z = (143 - 150) / 5 = -1.4
P(z < -1.4) = 0.0808
z = (145 - 150) / 5 = -1
P(z < -1) = 0.1587
0.1587 - 0.0808
0.0779
7.79%
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10)
z = (155 - 150) / 5
z = 1
P(z < 1) = 0.8413
z = (157 - 150) / 5
z = 1.4
P(z < 1.4) = 0.9192
0.9192 - 0.8413
0.0779
7.79%


