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September 21, 2014

September 21, 2014

Posted by **JOSH** on Saturday, October 3, 2009 at 3:44pm.

- Statistics -
**jim**, Saturday, October 3, 2009 at 5:06pmSince the flight is always fully booked, we can say that the luggage weight's mean is 8000 and the SD is 2000.

We're interested in the number of flights that is more than (300 / 2000 =) .15 SD above the mean.

Now we go to a z-score table - Google will provide, if you don' have one handy - and look up the value. The one I found says that 0.5596 of flights will be below the +0.15 SD mark, so that leaves .4404, or 44%, above it.

- Statistics -
**economyst**, Monday, October 5, 2009 at 6:47pmI dont think jim is correct.

The SD of X+Y = sqrt[var(X)+var(Y)+2cov(XY) ]

Assuming all air-travelers are independent of each other, the last term goes away. Var(X)=SD(X)^2 = 400

so SD = sqrt(100*400) = 200

take it from here.

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