ok, my question pretains mainly to 123 problemsb 80 and 81.

Problem 80: Charity receives 2025 contributions. Contributions are ind. and dist. with mean 3125 and std dev 250

Problem 81: Claims filed under auto insurance are normal with mean 19400 and std dev 5000.

In the solution for problem 80, the mean and variance were both multiplied by n and then plugged into the P(Z<X)=.9

In the solution to problem 81, just the variance is divided by n, buyt divided, not multiplied.

what was the difference in the problems. (I.E. why in problem 80 did we not divide by n for teh variance)

Thanks,

Chris

Problem 80: Charity receives 2025 contributions. Contributions are ind. and dist. with mean 3125 and std dev 250

Problem 81: Claims filed under auto insurance are normal with mean 19400 and std dev 5000.

In the solution for problem 80, the mean and variance were both multiplied by n and then plugged into the P(Z<X)=.9

In the solution to problem 81, just the variance is divided by n, buyt divided, not multiplied.

what was the difference in the problems. (I.E. why in problem 80 did we not divide by n for teh variance)

Thanks,

Chris

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