Math Is Fun Forum

Hi EMPhillips;

If you mean that the reflective barrier bumps you back to 3 then this is the transition matrix.

This is how I would set that random walk up.

Hi Shmeeztut;

The cost of the concert in 2004 is 385 dollars, since the cost in 2005 is 10% less  we can say that the cost of the concert in 2005 is 90% of  $385. (Remember 100% - 10% = 90%). Now just do 385 times by .9 (90%/100% = ,9) and this equals $346.50 This is the cost of the concert in 2005. This makes sense because we knew it had to be less.

The cost in 2004 was 10% greater than in 2003 that means it was 100% + 10% more or 110% this is just 110/100 or 1.1 (this is how you convert any percent to a decimal so you can calculate with it). We now divide the $385 by 1.1 and get $35. This how much more the concert in 2004 is. Just do 385 - 35 = $350 this is what the concert in 2003 costs. This again makes sense because it had to be less.

See if this makes anything clearer for you. Work a few more problems like this one and it might become a little bit easier. Also ask the teacher to help you out a little. If none of that helps, its not the end of the world, just repost here.

bobbym

Hi mathsyperson,

  The method I suggested would yield a good solution but not necessarily the optimal one. He should use your method to refine that solution, whether both of our ideas would yield the optimal solution in every case, I can't say.

   Looking at mathsypersons improvement, it might be wiser to alternately form the two lists biggest element and smallest in the first list. Then next biggest and next smallest in the second list and to alternate like this until the original list is exhausted.

bobbym

Hi Mathsisfun;

   If those results are correct about a nearly perfect liquid then they appear to have the first experimental evidence supporting the existence of strings. A serious slap in the face of Sheldon Glashow and the rest of the Ed Witten detractors.

bobbym

Hi nubemet;

   I have only heard of Galileo doing this type of experiment. I believe it was done from the leaning tower off Pisa (but this may just be a legend).

bobbym

Brilliant idea. If I remove my shoes and procure a hammer, I would be quite capable at hexadecimal.

Hi random_fruit;

   Take heart, it is much worse over here, where a high school senior math teacher just told me that none of his students were capable of making change from a cash register. None were able to compute a 15% tip even though they are being taught AP Calculus. Something called "Teaching to the test". Part of the new philosophy that it is cool to be stupid and uncool to be a nerd.

bobbym

Hi Jane;

   I discovered that about 10 years ago but didn't notice your method of combining them and promptly forgot about the whole idea. So I guess its yours and I will always remember it as Jane's lemma.

bobbym

Hi Jane;

   You say you are not  very familiar with methods of solving difference equations but yet you came up with the idea of splitting the sequence into 2 coupled difference equations, each handling every other term. I salute you.

bobbym

Hi Jane;

All of them react with water like this typical reaction for Sodium:

2 Na + 2H20 -> H2 + 2 NaOH

They form a strong base( NaOH - Sodium Hydroxide or lye) and release hydrogen gas. Magnesium which is not quite as active will still slowly release hydrogen if it is immersed in hot water. Thanks for finding this video because I had never seen Rubidium or Cesium when I was in class.

bobbym

Hi Tony;

  I also only found (3,1) and (5,3) and I searched up until 3^3211 + 5. Have no proof yet that these are the only ones.

bobbym

Hi Ganesh;
For #9

Solve for x and y in terms of m to understand how x and y behave when m varies:

After a lot of algebraic thrashing and some trial and error:

These values of m satisfy the constraints x>0 and y>0