3 is subtracted from two-thirds of n
2 answers:
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Answer:
The probability there will be between 280 and 360 column inches of classified advertisement
P(280≤X≤360) = P(-2≤Z≤2) = 0.9544
Step-by-step explanation:
<u><em>Step(i):-</em></u>
Given that the mean the population = 320
The standard deviation of the Population = 20
Let 'X' be the random variable in a normal distribution
Let 'X' = 280
Let 'X' = 360
<u><em>Step(iii):-</em></u>
The probability there will be between 280 and 360 column inches of classified advertisement
P(280≤X≤360) = P(-2≤Z≤2)
= P(z≤2) -P(z≤-2)
= P(z≤2)+P(z≤2)
= 2P(z≤2)
= 2×0.4772 ( from normal table)
= 0.9544