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Answers by Ryan S.

Percentage of heart attack survivors who use a difibrillator (answer)

There are some problems with how this question is worded, but here is how I interpret it. Let S be the patient is saved. Let D be a defibrillator is used. Let A be a defibrillator is in the area. The event that a defibrillator is used within 5 minutes is D∩A   We are...

Help!!!! (answer)

What you want is P(X<220)-P(X<170). A lot of technology tools will give you this directly, but if you want to convert the problem in to Z scores to use a table of the standard normal distribution, this is how you do it.   For X = 220 Z=(220-200)/50 = 0.4 For X = 170 Z=(170-200)/50...

Please help. I need to know how to do this by Friday morning (answer)

For simple linear regression the model is y = α + βx In this case, y is the final exam grade and x is the midterm grade. β=rxy(sy/sx) where rxy is the correlation coefficient, sy is the standard deviation of y, and sx is the standard deviation of x. α = ybar - β*xbar We...

What do you do to figure this problem? (answer)

Let M=male lizard ages, F=female lizard ages, ρ = correlation, Cov(m,f) = covariance   M = .75F ρ=Cov(M,F)/(σMσF) Cov(m,f) = E[MF] - E[M]E[F] = E[.75F*F] - E[0.75F]*E[F] = 0.75(E[F2]-E[F]2) = 0.75*Var(F) σM=.75σF   Var(F) = σF2 ρ = 0.75σF2 /...

Math help expected share question (answer)

This time I will say more about how to set up the Markov matrix. Let's let the first column be what happens to GTT customers. 75% stay with GTT (g) 5% go to NCJ (n) 20% got to Dash (d) The second column is what happens to NCJ customers 25% go to g 50% stay with n 25%...

Math help probability (answer)

This is an example of a Markov chain problem. Let x be the number of preferred drivers, let y be the number of satisfactory drivers, and let z be the number of poor drivers. Then we can set up a matrix and a vector this way. Matrix A              vector u 0...

annual risk (answer)

The CAPM model says that the return on an asset includes the risk free rate of return plus additional return based on the asset's risk relative to the market.   ra : expected rate of return of asset rf : risk-free rate of return rm : expected rate of return of market β :...

Came across this problem in my assignment... Not sure what to do. (answer)

This can be solved with a system of equations. Let x be the amount invested at 6% and let y be the amount invested at 8%.   You know that the total invested is 10,000. This yields one equation: x + y = 10,000   You also know that the interest earned on x plus the...

What is formula that I use for calculating expected values?: (answer)

The expected value is the sum of the products of all outcomes and the respective probabilities. In your example, the outcomes and the probabilities are listed below.   Outcome Probability 2             0.25   (tails, tails) 3    ...

2 random variables (answer)

First notation: E[X] means the expected value of X and equals the mean of X. E[X^2] means the expected value of X^2 and can be calculated given the mean and standard deviation of X. Var(X) = E[X^2] - (E[X])^2 and is equal to the square of the standard deviation of X. It follows that...