CPhill

I'll attempt to derive a "formula" for calculating this......

First, let's assume that all deposits are made at the first of the month (an "annuity-due")

Let "d" be the monthly deposit and let r be the geometric difference between successive terms of the sums in the annulty calculation. So, the sum of this annuity is given by:

S = [dr + dr^2 + dr^3 + ..... + dr^(n-1) + dr^(n) ]   where n is the number of months over the life of the annuity

Now, multiply this sum by (1/r) =

(1/r)S = (d + dr + dr^2 + .... + dr^(n-2) + dr^(n-1) ]

Subtracting the second sum from the first, we have

(1- 1/r)S = [-d + dr^(n)]  

(1 - 1/r)S = d [r^(n) - 1]

S = d [ r^(n) -1 ] / [ 1 - 1/r ]

S = d*(r) [ r^(n) -1 ] / [r - 1]

So.....d = 375    and r = (1 + .042/12) = 1.0035  and  n = 180    ...  So we have

S = 375(1.0035)[ 1.0035^(180) - 1 ] / [.0035]  ≈ $94,136.88

That's my best attempt......!!!!!!

Thanks for including that reference at the bottom, ND......

Excellent, ND !!!

That was one that could trip you up pretty easily if you're not careful........

"Thumbs" and Points......

I/m assuming that a = 2 + 3/4  = 11/4    ...    so we have

ab =  (11/4) * (4/5) .......cross-cancelling the "4s," we have .... 11/5   (or, 2 + 1/5, if you prefer)

Always check and see if you can "cancel" before you multiply....it simplifies things greatly......

Whoa there, ND...your first answer...... 72/7....... is correct

But this isn't equal to 7 + 2/7  which = 51/7

72/7 is actually   =  10 + 2/7

Be careful, here......

I'm going to fill in the blank, here. I'm assuming you want to know how many pennies you have.

The remaining coins =  215 - 89  = 126

And 2/3 of 126 = 84 pennies.

If this isn't what you wanted.....accept my apologies......

NinjaDevo's method is correct  !!!

Three letters are selected at random from the word "distance" find the probability of three vowels P(3 vowels).

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I see this one a little differently......we are counting all the sets that are possible when choosing any three things from eight =  C(8,3) = 56

Only one of these sets contain all three vowels in the word "distance."

So we have......... 1/56

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Can someone look at my answer and tell me if I'm correct, or not??

We want the wheel to come up "yellow" 7 out of 10 times....so we have  C(10,7)

And the number of possible outcomes is just  3^10

So we have  C(10,7) / 3^10  ≈ .002   ≈ 2/1000   ≈ 1/500

From the four aces, we want to choose any one of them = C(4,1)

Then, we want to choose any card from the other 12 ranks   = 12*C(4,1)

And the total number of possible "hands" is just C(52,2)

So we have

C(4,1) * 12C(4,1) / C(52,2)  ≈  .217  ≈ 21.7%