Answer:
The upper limit of a 95% confidence interval for the population mean would equal 83.805.
Step-by-step explanation:
The standard deviation is the square root of the variance. Since the variance is 25, the sample's standard deviation is 5.
We have the sample standard deviation, not the population, so we use the t-distribution to solve this question.
T interval:
The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So
df = 15 - 1 = 14
Now, we have to find a value of T, which is found looking at the t table, with 14 degrees of freedom(y-axis) and a confidence level of 0.95(
). So we have T = 1.761
The margin of error is:
M = T*s = 1.761*5 = 8.805.
The upper end of the interval is the sample mean added to M. So it is 75 + 8.805 = 83.805.
The upper limit of a 95% confidence interval for the population mean would equal 83.805.
Answer:
b: 4
Step-by-step explanation:
Answer:
D) 15/12 and 5/4
Step-by-step explanation:
Because when you cross multiply the ratios
15*4 and 12*5
making both ratios a proportion
they both = 60
The answer is: x = 400
Here's how I got my answer:
Step 1: Subtract .60 from both sides. Leave us with ![100=20+0.80x-0.60x](https://tex.z-dn.net/?f=%20100%3D20%2B0.80x-0.60x%20)
Step 2: Simplify
to
. Which leaves us with ![100 = 20 + 0.2x](https://tex.z-dn.net/?f=%20100%20%3D%2020%20%2B%200.2x%20)
Step 3: Subtract 20 from both sides. Which leaves us with ![100-20=0.2x](https://tex.z-dn.net/?f=%20100-20%3D0.2x%20)
Step 4: Simplify
to 80. Which leaves us with ![80 = 0.2x](https://tex.z-dn.net/?f=%2080%20%3D%200.2x%20)
Step 5: Divide both sides by 0.2. Which leaves us with ![80/0.2 = x](https://tex.z-dn.net/?f=%2080%2F0.2%20%3D%20x%20)
Step 6: Simplify
to 400. Which leaves us with our answer, x = 400