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 The mean weight of loads of rock is 47.0 tons with a standard deviation of 6.0 tons. If 16 loads are chosen at random for a weight chec

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The mean weight of loads of rock is 47.0 tons with a standard deviation of 6.0 tons. If 16 loads are chosen at random for a weight check, find the probability that the mean weight of those loads is less than 46.2 tons. Assume that the variable is normally distributed.

 

Can anyone answer this quickly please? I would appreciate it very much

 Nov 7, 2014

Best Answer 

 #1
avatar+23254 
+5

z-score for a sample:  z  =  [ (sample mean) - (known mean) ] / [ (std. dev. / √(sample size) ]

z  =  [ 46.2 - 47 ] / [ 6.0 / √(16) ]  =  -.9428

Now find the normalcdf for a z-score this small (or smaller).

 Nov 7, 2014

1+0 Answers

 #1
avatar+23254 
+5
Best Answer

z-score for a sample:  z  =  [ (sample mean) - (known mean) ] / [ (std. dev. / √(sample size) ]

z  =  [ 46.2 - 47 ] / [ 6.0 / √(16) ]  =  -.9428

Now find the normalcdf for a z-score this small (or smaller).

geno3141 Nov 7, 2014

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