AP Statistics Homework Help Please? pt II? - ap for pt school
A mechanical assembly (Figure 7.12) consists of a shaft with a bearing at each end. The total length is the sum X + Y + Z-axis length of X and Y and Z of length steps. These lengths can vary from one to another part of the production, independently of each other and with normal distributions. The axis x 11.6 cm in length and has an average standard deviation of 0.001 inches, while the length of each level, Y and Z is an average of 0.5 inches and a standard deviation of 0.003 inches.
Figure 7.12 - Link: http://i257.photobucket.com/albums/hh201/reeserpie/figure-07-12.jpg
(b) is a common practice in the industry, "state of natural tolerance" of the parties in the established in paragraph (a). An engineer who does not know the statistics thought to add tolerances, so that the natural tolerance of the total length of the assembly (the shaft and two bearings) is 12 cm d, where d = d1 + 2 D2. Here you will find the standard deviation of the total length of X + Y + Z.
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Wednesday, February 3, 2010
Ap For Pt School AP Statistics Homework Help Please? Pt II?
1 comment:
Let X and Y be independent random variables and variance σx ² ² σy. Let a, b, c, and be consistent. Let W = ax + by + c
The average of W:
E (W)
E = (ax + by + c)
= AE (X) + bE (Y) + c
The difference W = ax + by + c:
Var (W)
Var = (ax + by + c)
Var = (ax + by) (Due to constant additive has no influence on the distribution of data)
= Var (aX) + Var (by) (This applies only if X and Y are independent)
A ² = Var (X) ² + b Var (Y)
= (Aσx) ² + (bσy ²)
It is easy to three random variables that we have only for a third term to extend
Var ((X + Y + Z) = Var X) + Var (Y) + Var (Z)
= 0.001 ^ 2 ^ 2 + 0.5 + 0.5 ^ 2
= 0.500001
Deviation is the square root of the variance
std dev = sqrt (0.500001) = 0.7071075
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