Recent content by veronica1999

Question: What is the area enclosed by the lemniscate r2 = -25cos(Ѳ)? The answer is 25. I can't seem to set up the integral for this question correctly. I know that the area enclosed by a polar curve is obtained by the integral(r2/2) dѲ, but I can't determine what the interval of integration...

Actually I just realized my mistake. ^.^ I wasn't getting the correct anti-derivative. Thank you for your help!

Thank you. That makes a lot of sense. The only thing I'm wondering now is why I kept getting the wrong answer. I was trying to use a similar approach (I had the same integral but different intervals of integration). I integrated from -3 to 3 and doubled the volume instead. Why did this not...

A solid has a circular base of radius 3. If every plane cross section perpendicular to the x-axis is an equilateral triangle, then it's volume is I keep on getting 18 root 3. But the answer is 36 root 3. Could I get some help? Thanks.

Thanks! Now I think I understand how to correct the overcounting. I am still amazed how you did it so easily. First, I made the problem simpler and then applied what you did above. Let's say there are 4 people A,B,C,D There are a total of 3x3x3x3 outcomes. And 4C2 x3x3 to make a pair. In this...

7 people are having a water balloon fight. At the same time, each of the 7 people throws a water balloon at one of the other 6 people, chosen at random. What is the probability that there are 2 people who throw the balloon at each other? I am having a lot of trouble on this one. First, I...

Re: dice problem Oops... Thanks!:D

Five standard 6-sided dice are rolled. What is the probability that at least 3 of them show a six? I am surprised my answer is wrong. First the total outcomes are 6x6x6x6x6=7776 Successful outcomes 10x6x6=360 There are 10 ways to choose 3 from 5 and then the remaining 2 can be any number...

Re: find the derivative Thank you! Now it is clear.:D

Re: find the derivative Yes! I promise i will learn it soon.

I don't understand why my answer is wrong...

Thank you!(Smile)

Thanks for your help but the answer is 162. i think the answer multiplied another 6. ~Veronica

Forty slips are placed into a hat, each bearing a number 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 with each number entered on four slips. Four slips are drawn from the hat at random and without replacement. Let...

Re: coins Thanks! Now it is absolutely clear.:D