ave. payment $982, standard dev. $180; find prob. payment is

MRS.FREE

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Feb 28, 2009
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The average monthly mortgage payment including principle and interest is $982 in the US. If the standard deviation is approximatly $180 and mortgage payments are approximatly normally distributed, find the probability that the monthly payment is:

more than $1,000

1,000-982=18/180=.1
.1=.5398
1-.5398=.4602

more than $1475

1475-982=493/180=2.7
2.7=.9965
1-.9965=.0035

between $800 and $1150

800-982=-182/180=-.1
-.1=.1587

1150-982=168/180=.93
.93=.8238

.8238-.1587=.6651


I'm really not sure if I'm doing this correctly, can someone please help me?
 
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