# interval

1. ### Help explain why teacher says rating is "interval" and not "ordinal"

Hello, I got a question wrong on a test and I can’t understand why. It was a simple question to identify if performance rating was ordinal or interval. I put ordinal since I thought rating wouldn’t have a true “interval” between each number. My teacher sent me a message saying "You're...
2. ### Rate of change of trig function

Hi, I hope someone can help. I'm suppose to state two intervals where the function y = 3cos(4x)-4 has an AROC that is zero. I'm wondering why my textbook only gave the solution of 0 < x < pi/2, and pi < x < 3pi/2 ? Wouldn't the two intervals 0 < x < pi/2, and pi/2 < x < pi be just as correct...
3. ### Absolute Extrema

Find the absolute extrema of the given function on each indicated interval. f(x) = |2x| - |x - 2| on (a) [0,1] and (b) [-3,4]
4. ### Trig equation over specified interval

2sin(x-7) + 6 = cos(2x-10) + 8 Solutions in [6,14] I don't even know where to begin. If there wasn't a constant I would set it to 0 and try sum to product then find zeros. Then there's dealing with the applied interval. Ken T. Also did a rough sketch to make sure it wasn't a trick...
5. ### Interval of Convergence for differing odd/even coefficients of power series

Hello, I am studying for a midterm this week. One of the practice problems is to find the radius of convergence of \sum_{n=0}^{\infty} a_n x^n where a_n = 5^n if n is odd and a_n = 1/3^n if n is even. It took me a while to hazard a guess that I take the smaller of the two radii? Then a =...
6. ### Interval of Convergence of Infinite Series

Hi I have two questions asking me to find the interval of convergence of an infinite series: 1. Sum n=1 - infinity of: (2x)^n/(n^2+1); and 2. The Taylor series (or actually McLaurin series I think) for ln(1+x) about x=0 ie sum k=1 to infinity ((-1)^k*x^k)/k The actual words I have used are...
7. ### Determine the following set in interval form

i have this very rare problem for me in interval... can anyone help me on this please.. thank you
8. ### 99% one sided upper bound confidence interval for mean?

I have a random sample X1....X24 from normal distribution with mean u and variance sigma^2 = .73. If Xbar = 3.3 then what is a 99% one sided upper bound confidence interval for u?
9. ### Two sided confidence interval

Hey guys quick question. I have a required mean of 50, a random sample of 150, and the sample mean of that data is 51.3. The standard deviation of this sample is 5. I have to find a 99% two sided confidence interval for the mean of the new data. So far I have Xbar +...
10. ### Two sided confidence interval

I have a random sample of 185 lightbulbs. 18 of them had a defect. I have to find a two-sided confidence interval for the true proportion of defective lightbulbs. I was hoping someone could walk step by step how to do this problem. Thanks!
11. ### Find all the solutions on the interval [0, 360°). sin(5x)=0

1. Find all the solutions on the interval [0, 360°). sin(5x)=0 2. Solve the equation on the interval [0, 360°). 2 cos^2(x) + 5 cos(x) - 3 = 0 I think I found the answers: I think the answers to number 1 is 0, 36, 72, 108, 144, 180, 216, 252, 288, and 324 degrees? I think the answer...
12. ### Interval Estimation unknown mean

I am given information of standard deviation is 8.5 and I am supposed to develop a 95% confidence interval with that. The answer in the back of the book says the answer is 39.13 to 41.49. How would I come up with that answer? I have spent a couple hours trying to figure this out and decided it...
13. ### Probability: events selected from unit interval

Hi I'm having trouble determining which events this question is referring to maybe this wording makes more sense to you than it does to me. A number U is selected from the unit interval. Let the events A and B be A= U differs from 1/2 by more than 1/4 and B=1-U is less than 1/2. Find the...
14. ### Confidence Interval Question

How would I solve this problem? A study of the fall lobster catch showed that for 35 lobsters lobsters selected at random the mean weight was 2.9 pounds with a standard deviation of 0.6 pounds. How many more lobsters should be included in the sample if we want to be 99% confident that the...
15. ### Checking the endpoints of the interval of convergence

These problems are fairly easy, but it's the arithmetic with the terms that gets me. I don't know if I simplified the terms highlighted in yellow.
16. ### Checking the endpoints of the interval of convergence

I just wanted to check if my conclusion about the interval of convergence is correct.
17. ### Finding the sum of a series within its interval of convergence

As you see I've successfully found the sum of the series for the original given series, which is 4/(x-5) as shown in the image. I was then asked to differentiate the original series and to find its sum. Now from what I know, in order to find the sum = a/(1-r), you'll need to find the variables a...
18. ### Finding radius and interval of convergence using ratio test

Apparently my answer of Radius = 1/49 is wrong. I've tripled check my work. I keep getting the same answer.
19. ### Find the radius and interval of convergence

I got the radius right, 6. The interval I got was -6 < x < 6. I checked both endpoints and found that it diverges for both endpoints. I think that's wrong because the choices doesn't indicate both endpoints diverging. Attached is the question and my work.
20. ### Confidence Interval Help

The telephone company was interested in measuring the average daily usage in minutes for household telephones in a specific area in order to determine whether this rate is different from a state-wide average daily usage for households. Suppose that a random sample of nine households were sampled...