A pet food company is concerned that their pet food must have a certain % of the mineral zinc in the food. Too little and dogs get very sick. If the machinery is working correctly, the average zinc is u = .375 gram/lb of food. They sample 25 bags of food and find: x = .359 grams o = .05 grams The firm wants to know if their pet food is healthy. They decide on a 95% level of significance. Do the Z test. They ask you to perform the analysis. a) State the null and alternative hypotheses. Но: На: b) Draw a picture/graph of what you are trying to find. c) Find the critical value you will use. d) Compute the test statistic (from the data) e) What do you conclude? Why?
Percentage
A percentage is a number indicated as a fraction of 100. It is a dimensionless number often expressed using the symbol %.
Algebraic Expressions
In mathematics, an algebraic expression consists of constant(s), variable(s), and mathematical operators. It is made up of terms.
Numbers
Numbers are some measures used for counting. They can be compared one with another to know its position in the number line and determine which one is greater or lesser than the other.
Subtraction
Before we begin to understand the subtraction of algebraic expressions, we need to list out a few things that form the basis of algebra.
Addition
Before we begin to understand the addition of algebraic expressions, we need to list out a few things that form the basis of algebra.
![### Zinc Content Analysis in Pet Food
A pet food company is concerned that their pet food must have a certain percentage of the mineral zinc. Insufficient zinc levels can make dogs very sick. If the machinery is working correctly, the average zinc content is supposed to be \( \mu = 0.375 \) grams per pound of food.
They sample 25 bags of food and find:
- Sample mean (\( \bar{x} \)): \( 0.359 \) grams
- Standard deviation (\( \sigma \)): \( 0.05 \) grams
The firm wants to determine if their pet food is healthy by conducting a Z-test at a 95% level of significance.
#### Analysis Steps:
a) **State the Hypotheses:**
- **Null Hypothesis (\( H_0 \)):** The average zinc content is \( 0.375 \) grams per pound (\( \mu = 0.375 \)).
- **Alternative Hypothesis (\( H_a \)):** The average zinc content is different from \( 0.375 \) grams per pound (\( \mu \neq 0.375 \)).
b) **Draw a Picture/Graph:**
- Although not depicted here, a graph involves plotting a normal distribution curve with the mean of \( 0.375 \) grams at the center. Highlight the rejection regions on both tails based on the Z-test critical values.
c) **Find the Critical Value:**
- For a 95% confidence level, the Z critical values are approximately \( \pm 1.96 \).
d) **Compute the Test Statistic:**
- The Z-test formula is:
\[
Z = \frac{\bar{x} - \mu}{\frac{\sigma}{\sqrt{n}}}
\]
- Substituting the values,
\[
Z = \frac{0.359 - 0.375}{\frac{0.05}{\sqrt{25}}} = \frac{-0.016}{0.01} = -1.6
\]
e) **Conclusion:**
- Since \(-1.6\) is within the range of \(-1.96\) to \(1.96\), we fail to reject the null hypothesis. Thus, there is not enough statistical evidence to suggest the average zinc content is different from \( 0](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fe9ff3616-361e-41ff-bd24-ad1fe99bbb43%2Fd0ae1ffe-8676-457a-a8a8-1d3b1cc7256c%2Fjqee11h_processed.jpeg&w=3840&q=75)
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