In: Math
The probability that a certain kind of flower seed will
germinate is .80.
(a) If 194 seeds are planted, what is the probability that
fewer than 141 will germinate? (Round standard deviation
and your final answer to 4 decimal places.)
Probability()
(b) What is the probability that at least 141
will germinate? (Round standard deviation and your final
answer to 4 decimal places.)
Probability ()
Solution:
Given that probability, = 0.80 and number of seeds planted, = 194
Since = 194 (0.80) = 155.2 and = 194 (1 - 0.80) = 38.8 both are greater than 5, we use normal approximation to binomial distribution.
Mean, = = 194 (0.80) = 155.2
Standard deviation, = = = 5.5714
a. Using continuity correction, X < 141 will be X < 140.5
The respective Z-score with X = 140.5 is
Z = -2.64
Now, we use Z-tables to find the probability Z less than -2.64
P (Z < -2.64) = 0.0041
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b. Using continuity correction, X 141 will be X > 140.5
The respective Z-score with X = 140.5 is
Z = -2.64
Now, we use Z-tables to find the probability Z greater than -2.64
P (Z > -2.64) = 1 - 0.0041 = 0.9959