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1. ### Normally distributed random variable and probability

It's an online homework assignment. I talked to my teacher and he said the site was having issues with the rounding. Thanks for the help!
2. ### Normally distributed random variable and probability

Homework Statement The top-selling Red and Voss tire is rated 60000 miles, which means nothing. In fact, the distance the tires can run until wear-out is a normally distributed random variable with a mean of 70000 miles and a standard deviation of 5000 miles. A: What is the probability that...
3. ### Comp Sci Java Tokenizer Issues

I'm trying to make a program that prompts a user to enter a binary number and then converts the string into integers by using Integer.parseInt. Right now though, I'm having trouble with tokenizing the string. My code works when I use the predefined variable temp but not when I enter the same...
4. ### Changing Delimiters

I'm entering it like 14:00. I tried changing the variables to integers and used nextInt, but the program waits for me to do something else after that. I tried entering 14:00 again after that just to try something and got an InputMismatchException, if that helps.
5. ### Changing Delimiters

I'm trying to write a program that converts military time to civilian time (24-hour to the standard 12-hour) but I'm having trouble with changing the delimiter to ":". I've tried re-working the code every way I can think of and it still won't work properly. import java.util.Scanner; public...
6. ### Proof of Limits: a^(1/n)

Homework Statement Let a>1. Prove the limit as n goes to \infty of a1/n = 1. The Attempt at a Solution Given \epsilon > 0, \foralln>N, |a1/n-L|<\epsilon and N=(a-1)/\epsilon. |a1/n-L| = a1/n-1 ...and that's where I get confused. I know that I have to multiply (a1/n-1) by something...
7. ### Methods, Classes, and Variables

My professor assigned a project that has the user enter information for an Object called Student which is derived from Person. The information is a name, an id number, two scores, an average, and the letter grade equivalent of the average. I'm having trouble sorting the student's according to...
8. ### Arrays and Loops Problem

I'm having issues with a sorting class that I'm trying to call from my main program, TestStudent. I don't think it's taking the user's input correctly when I try to read it into an array but I can't figure out why. class Student: public static void selectionSort(double[] numbers) {...
9. ### Comp Sci Java Calling Methods Problem

I'm trying to create a program that derives a class named Student from the class Person, and then I'll test everything in the main program in TestStudent. What I'm having trouble with at the moment, is calling the methods correctly. Whenever I try to call a method in the main program, I get this...
10. ### Proof with rationals and irrationals

Homework Statement Show that any rational in the interval (0,1] can be expressed as a finite sum r=1/q1+1/q2+...+1/qn where the qj are integers and q1<q2<...<qn. Homework Equations The Attempt at a Solution Let x\inQ and 0<x\leq1. Prove \existsq1, q2, ..., qn\inN with...
11. ### State and prove a natural generalization

So it's asking for a proof of the form (x1+x2+...+xn)/n \geq \sqrt[n]{x1x2...xn} . So, I should prove the Arithmetic-Geometric Mean Inequality?
12. ### State and prove a natural generalization

Homework Statement State and prove a natural generalization of "prove that for any three positive real numbers x1, x2, x3, x1/x2 + x2/x3 + x3/x1 \geq 3. Homework Equations AG Inequality is used in subproof (x1/x2 + x2/x3 + x3/x1 \geq 3) The Attempt at a Solution I don't know what...
13. ### Simple Proof

Homework Statement Let X={1/n: n\inN} (where N is the set of natural numbers) i) Does inf(X) exist? ii) What is inf(X)? Homework Equations The Attempt at a Solution I think I should try to prove inf(X) exists by considering it a Lower Limit, but I don't know how to go about...
14. ### Java Java: Airplane Seating Chart

I've been working on this and I can't figure out why, exactly, it's not working properly. I can reserve a seat 4A but when I try to reserve seat 6A, the output includes a line of string that says "The seat you requested is unavailable. Please make another selection." yet it still let's me make...
15. ### Proving the Greatest Lower Bound Property with

Homework Statement Use part (a) to prove the Greatest Lower Bound Property. (a): If M is any upper bound for A, then: x\in(-A), -x\inA, and -x\leqM. Therefore x\geq-M, hence -M is a lower bound for -A. By the Least Upper Bound Property, inf(-A) exists. If inf(-A) exists, then...
16. ### Proving that the Archimedean axiom is true

S is the supremum of the set because the set is bounded above by b/a, which is what sup([b]N[/]) is defined as at the beginning of the proof (b/a ≥ n).
17. ### Proving that the Archimedean axiom is true

Oh. Um, it exists because S is the supremum of the set?
18. ### Proving that the Archimedean axiom is true

I would choose n to be close to S, or S-1<n<S. So for any n bounded above by S but greater than S-1, if n+1>S, then there exists a natural number not bounded above by S. And so on, and so on. Is that specific enough?
19. ### Proving that the Archimedean axiom is true

If n+1>S, then there exists a natural number not bounded above by S. This is a contradiction as the set N is the set of whole positive integers and adding 1 would not exclude any n previously in the set N. Is that right?
20. ### Proving that the Archimedean axiom is true

Homework Statement Show that the Archimedean axiom O5 follows from the Least Upper Bound Property O6, together with the other axioms for the reals. Homework Equations O5 = [if a,b > 0, then there is a positive integer n such that b<a+a+a+...+a (n summands)] or [if a,b > 0, then b < na or b/a <...
21. ### Real Analysis Problem

Thanks! I got through part (a) by proving (A+B) must be nonempty and then proving that there was an upper bound in (A+B) since both A and B had upper bounds, using the Least Upper Bound Property to prove that there must be a least upper bound since there was an upper bound to begin with. I'm...
22. ### Proof by Induction

Homework Statement Prove that for any positive h and any integer n\geq0, (1+h)n\geq1+nh+\frac{n(n+1)}{2}h2. Homework Equations None. The Attempt at a Solution I proved that P(0) is true (1\geq1). The rest of the proof goes as follows: Assume K\inZ (the set of integers) and P(K)...
23. ### Real Analysis Problem

Homework Statement (a) Suppose that A and B are nonempty subsets of R. Define subsets -A={-x: x\inA} and A+B={x+y: x\inA and y\inB}. Show that if A and B are bounded above, then the greatest lower bound of -A = - least upper bound of A and the least upper bound of (A+B) = the least upper bound...
24. ### Statistics and Tchebysheff's theorum

Homework Statement Let k\geq1. Show that, for any set of n measurements, the fraction included in the interval \overline{y}-ks to \overline{y}+ks is at least (1-1/k2). [Hint: s2 = 1/(n-1)[\sum(yi-\overline{y})2]. In this expression, replace all deviations for which the absolute value of...
25. ### Finding an Equation of a Plane

Okay, so just to be clear, to get the vector in the plane I would take the dot product of <2, -3, 7> and a vector of variables, say <a ,b, c> and set it equal to 0. I would get a final equation of 2a-3b+7c = 0. And this would be the equation of a plane that goes through (2, 2, -1) and is...
26. ### Intersection of a Curve and a Surface

1. At what points does the curve r(t)=ti+2tj+t2k intersect the surface z = x2+y2-100? Give the coordinates of the points. 2. Given equations above. 3. r(t)=<t, 2t, t2> z = x2+y2-100 (t2) = (t)2+(2t)-100 -4t2 = -100 t = sqrt(25) = +/- 5 when t = 5, (5, 10, 25) when t = -5 (-5, -10, 25) This...
27. ### Finding an Equation of a Plane

1. Find an equation for the plane which goes through the point (2, 2, -1) and which is parallel to the plane 2x-3y+7z = 100. 2. x = x0+ta y = y0+ta z = z0+ta 3. First I found the parametric equations of a line parallel to the plane by using the vector <2,-3,7> from the equation...
28. ### Parametric Equations

1. Find parametric equations for the line joining the points P = (1,2,-1) and Q = (5,7,5).[/b] 2. x = x0+ta y = y0+tb z = z0+tc 3. v = <(5-1), (7-2), (5+1)> so v = <4,5,6> and since v is a vector in the direction of the line and should be able to be placed in the above...
29. ### Mathematical Proof

Oh. It tells me that g(f) is not one-to-one. But if that's the case, shouldn't f(x1) = f(x2)? I thought that that was the other part of the definition of not being one-to-one, that if the inputs are different then the outputs should be the same. And since f(x1) and f(x2) are the inputs in this...
30. ### Mathematical Proof

[b]1. Assume that f : A -> B and g : B -> C and that f is not one to one. Prove that g(f) is not one to one. [b]2. one-to-one: x1 != x2 and f(x1) != f(x2) not one-to-one: f(x1)=f(x2) and x1 != x2 [b]3. The start of the proof should go as follows: Assume f: A->B, g: B -> C, f is not...