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#1 Re: Help Me ! » um hi i need help on something... » 2008-11-01 15:38:20

That is to much work.......this is how you do it.

Using the 21.5 cm side, fold it diagonally so that the side lines up with the side that is 28cm.  This will leave you with 6.5cm to complete the full length.

Now using this length 6.5cm, line it up to the width 21.5cm, and you will be left with 15cm exactly to complete the width.

#2 Re: Exercises » Compound Interest » 2008-11-01 14:31:57

If you want to withdraw 25 000 at the end of each year, for the next 7 years, you must invest $144 165.0453.

We can check by the following....

The interest of 5% compounded quarterly may be written as (1.0125)^4 (total interest earned after each year on amount still invested).

Amount Invested:  $144 165.0453

After Year 1:  $144 165.0453 x (1.0125)^4 = 151 509.5821 after one year subtract 25000.   Amount still invested: $126 509.5821

After Year 2:  $126 509.5821 x (1.0125)^4 = 132 954,6554 after two years subtract 25000.  Amount still invested: $107 954.6554

After Year 3:  $107 954.6554 x (1.0125)^4 = 113 454.4417 after three years subtract 25000.  Amount still invested: $88 454.44168

After Year 4:  $88 454.44168 x (1.0125)^4 = 92 960.78301 after four years subtract 25000.  Amount still invested: $67 960.78301

After Year 5:  $67 960.78301 x (1.0125)^4 = 71 423.068 after five years subtract 25000.  Amount still invested: $46 423.068

After Year 6:  $46 423.068 x (1.0125)^4 = 48 788.10684 after six years subtract 25000.  Amount still invested: $23 788.10684

After Year 7:  $23 788.10684 x (1.0125)^4 = 24 999.999996 after seven years subtract 25000.  Amount still invested:  $0.00

#3 Help Me ! » Cominatorics- Man Walking.... » 2008-11-01 13:43:59

musician_14
Replies: 1

Sam wants to go from one street corner in a city to another one nine blocks east and six blocks north. Assume the streets are laid out as a square grid,.

A) How many ways may Sam choose the fifteen block walk?

B) How many ways may Sam choose the firteen block walk, if he does not want to walk through the (3,3) intersection? (noted by "X")

        Here is a diagram for B).

               __ __ __ __ __ __ __ __ __
              |   |   |    |   |   |   |    |   |   |
               __ __ __ __ __ __ __ __ __
              |   |   |    |   |   |   |    |   |   |
               __ __ __ __ __ __ __ __ __
              |   |   |    |   |   |   |    |   |   |
               __ __ __ __ __ __ __ __ __
              |   |   |    |   |   |   |    |   |   |
               __ __ __X__ __ __ __ __ __
              |   |   |    |   |   |   |    |   |   |
               __ __ __ __ __ __ __ __ __
              |   |   |    |   |   |   |    |   |   |
               __ __ __ __ __ __ __ __ __

#4 Re: Help Me ! » Permutations and combinations » 2008-11-01 13:21:28

That is comfirmed.

There are 8x10x10 x 10x10x10x10 different telephone numbers generated using the first condition (no 0's or 1's in first digit)
8x10^6 = 8 000 000 .

Now for the second condition, we place the digits 911 and 411 as the first 3 digits and figure out how many ways this can be done.
For 911:  1x1x1 x 10x10x10x10.  This can be done in 10^4 = 10 000 ways.
For 411:  1x1x1 x 10x10x10x10.  This can be done in 10^4 = 10 000 ways.
Since we do not want this to happen, subtract this from the number we found in condition 1.

We obtain that

8 000 000 - 10 000 - 10 000 = 7 980 000

Thus, there are a total of 7 980 000 ways to generate the new seven digit numbers for the new area code.

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