1. ## Hypothesis testing [resolved]

Hey guys i need your help again with a problem im having trouble getting my head around.

72 400-gram soil samples from a specific area were sampled, dried and analyzed for cyanide levels. The cyanide concentration (in mg / Kg) was determined using an infrared microscopic sample. The samples resulted in a mean cyanide level of 84 mg/Kg with a standard deviation of 80 mg/Kg. Test the hypothesis, using α = 0.01, that the true mean cyanide level in this area falls below 100 mg/Kg.

I know that i am to use a single tailed test, but when i do the math i end up with a negative number. Im using the formula Z=y-u/s*sqrt N
Is that the correct way to approach this?

2. ## Re: Hypothesis testing

I found that i had the right approach but i had the formula confused. I used z=y-u/(s/sqrt n), i then found the rejection region and observed.

3. ## Re: Hypothesis testing

Originally Posted by jwill212
never mind, got it
I've changed your post title so it's clear it's resolved. It can be nice in cases like these to post how you solved the problem in case anyone else is hunting for the answer to a similar problem.

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