Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

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#2 Re: Help Me ! » pools and Time » 2010-05-11 08:31:42

So it's 7&42, 8&24, 9&18, 10&15, 12&12 (typo i guess,  for x-6=6, y-6=12, should be =6), a total of 9 possibilities?

#3 Re: Help Me ! » pools and Time » 2010-05-11 05:04:56

But, wouldn't those be less than 6 Hrs?, A tap is helping the other tap, which is equal or less than 6hr, that's gotta be faster than 6 hr!!

#4 Re: Help Me ! » pools and Time » 2010-05-11 04:51:49

Why, Please explain, Thank you

#5 Help Me ! » pools and Time » 2010-05-11 04:42:16

iamfriendly
Replies: 8

So we were doing the Gauss Math Contest (no worries, Im not cheating, back home to have lunch). So the Last qustion was this:

In a garden, the gardener opens Tap A and Tap B to fill his pool with water. That took 6 hours. The length of time of one of the Tap fill the pool indivisually would be x. How many possibilities are x (now obviously it doen't matter if it's Tap A or B,)?

Choices a) 5       b) 6          C) 9            d) 10             e)12

This may seems very easy to many people out there., but if one of you can Help Me, I would really appreciate your help

P.S. I was able to come up with only 12hr&12hr for the taps, OH yeah, only "positive interger" hours (e.g. 3 hr, not 3 1/4 hrs)

#11 Re: Exercises » Middle School Mathematics » 2010-04-25 08:58:01

fast typing, bobbym! that was really fast! and by the way, how did you do the click thing-ie??

#14 Re: Exercises » Strategies » 2010-04-12 12:23:50

Hi;

Here are my ideas :

1. I don't know if this counts as algorithms, but knowing the squares of numbers under 20 could be very helpful (like   
   Anakin had said), especially in the Pythagorean Theorem. Say you memorized 19², then immediately you may tell that   
   19x38 is 722 (19^2=361, 361*2=722)
2.Thing like 33*27 equals to (11*3)*(3*9)=11*81=891 Rearranging factors.
3. In addition, try to match up numbers that makes a multiple of 10 (like tidy numbers, you said)
4. For a multiplication of 11: (say 11x44) first write down the left-most digit, (i.e. the 4) then write down the sums of adjacent numbers starting from the left-most digit. (e.g., thousand+ hundreds, hundreds+tens, tens+ones)and stop after calculating the tens digit and the ones digit. If any of the sums exceeds 9, add 1 to the previous sum. So now we have 48_
Finally, write down the ones digit. so 44*11 =484 in the same way, 11x34=374, 11x345=3795, 11x765=8415. This may be confusing, and useless but just interesting to point out (and the fact is that you probably know this already).
5. At the last, I say, practise will make anyone better and faster at almost anything. If you practise enough times, you can just tell the anwser without pondering. Just practise and you might find some neat strategies of arithmetic

#15 Re: Help Me ! » Plz Help, please ! » 2010-04-06 13:28:02

Hi;

  Thank you for your assistance as well as your patience upup big_smile

  Just last night (in bed, before reading your explanation) I was thinking and I found :

       for 2x = 5y ==> 1x=2.5y==> 1y= 0.4x ===> x+y=1.4x

       Lowest multiple of 1.4 is 7 then yeah.....
 
    a slight variation of your second method,  basically

  Just, like, sharing ideas if you don't mind.
  The 1st is really helpful, not that the 2nd one isn't, Thank you
  'Night, See you around

#16 Re: Help Me ! » Max and Min Problem » 2010-04-05 13:26:10

that's probably why you're legendary

#17 Help Me ! » Plz Help, please ! » 2010-04-05 12:47:45

iamfriendly
Replies: 2

Hi guys, here is the question:

      The integer numbers x and y satisfy the equation 2x=5y

      Only 1 of the following can be the sum of x and y
 
      2012,         2011,      2010,        2009,           2008

The standard anwser is 2009. The question is why??

Any thought might be a helpful hint to others.

Please help wave

#20 Re: Maths Is Fun - Suggestions and Comments » Convert percentage to decimal » 2010-02-21 04:56:41

Well, in my opinion, moving the decimal point is easier than moving all the digits

#21 Re: Introductions » Hello y'all!! » 2010-02-21 04:21:55

Gotcha! and yes of course, thank you

#22 Re: Introductions » Hi to everyone » 2010-02-21 04:20:22

Hey, Bobbym, thanks for all the help!!

#23 Introductions » Hello y'all!! » 2010-02-21 04:12:13

iamfriendly
Replies: 3

I am a middle school student from Markham, ON, Canada. I just joined a couple of months ago, didn't fave this forum that much, but now I realise how interesting, useful, and helpful this turned out to be.

#24 Re: Help Me ! » Probability related.....probably » 2010-02-20 07:35:23

I got
2     any different anwsers? please HELP
5

#25 Re: Formulas » Tests For Divisibility » 2010-02-20 07:28:26

thanks for the divisibility rule of 7. was always trying to find that ...

BUt u could just use long division in the mean time.....

any way, up

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