# Math Help - Advanced Stats

Q. If at some time in the future a sample of 50 bars are measured, and a mean value is found of 8.12 mm with a standard deviation of 0.14 mm. Test whether this sample
has changed from the original batch to a statistical significance of 95%.

n=50, μ = 8.12, σ = 0.14,

z = [ μ - x ] / sqrt(n) / σ

how do i get x??

2. Originally Posted by tone999
Q. If at some time in the future a sample of 50 bars are measured, and a mean value is found of 8.12 mm with a standard deviation of 0.14 mm. Test whether this sample

has changed from the original batch to a statistical significance of 95%.

n=50, μ = 8.12, σ = 0.14,

z = [ μ - x ] / sqrt(n) / σ

how do i get x??
There's no data given for the original batch so how can a comparison be made with a future batch?