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probability distribution

Profits (X ) in an industry consisting of 100 firms are normally distributed with a mean value of $1.5 million and a standard deviation of $120,000. Calculate :

(a) P(X<$1.3 million)

(a) P($1200,000 £ X £ $1,400,000)
Suppose a random sample of 10 firms gave a mean profit of $900,000

(b) Establish a 95% confidence interval for the true mean profit in the industry.

(c) Which probability distribution do you use? Why?

Solution Summary

Establish a 95% confidence interval for the true mean profit in the industry.

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