Answer:
There is not evidence that the population mean waiting time is different from 3.9 minutes.
Step-by-step explanation:
From the question we know that the size (n), the mean (x) and the standard deviation (s) of the sample are 81, 4.05 minutes and 0.9 minutes. Additionally, we are going to decide if the waiting time is different or not form 3.9 minutes, so the null and alternative hypotheses are:
H0: m=3.9
H1: m≠3.9
Where m is the mean of the population.
Then, <em>we don't need to be concerned about the shape of the population distribution because the value of the n is bigger than 30</em> and we can use the statistic z as:
![z=\frac{x-m}{\frac{s}{\sqrt{n}}}](https://tex.z-dn.net/?f=z%3D%5Cfrac%7Bx-m%7D%7B%5Cfrac%7Bs%7D%7B%5Csqrt%7Bn%7D%7D%7D)
So, replacing the values, the test statistic is:
![z=\frac{4.05-3.9}{\frac{0.9}{\sqrt{81}}}=1.50](https://tex.z-dn.net/?f=z%3D%5Cfrac%7B4.05-3.9%7D%7B%5Cfrac%7B0.9%7D%7B%5Csqrt%7B81%7D%7D%7D%3D1.50)
On the other hand, the p value for this test is calculated as:
p value = 2P(z>1.50) = 2(0.0668) = 0.134
Taking into account that the p value is bigger than the level of significance 0.01, the null hypothesis is not reject, and there is not evidence that the population mean waiting time is different from 3.9 minutes.
Answer:
<u>The correct answer is 5/24 or 0.21</u>
Step-by-step explanation:
1. Let's review all the information given to answer the question correctly:
Science class in seventh grade = 4 girls and 4 boys
Science class in eighth grade = 5 girls and 7 boys
2. What is the probability that both students selected for the competition are girls, a seventh grader and an eighth grader?
These are independent events, therefore:
Probability of two independent events = Probability of A * Probability of B
Probability of both students selected for the competition are girls = 4/8 * 5/12
Probability of both students selected for the competition are girls = 20/96 = 5/24
<u>The correct answer is 5/24 or 0.21</u>
It can be in multiple forms. 15 to 40 or 15:40