juriemagic

I'll give the answer as they have it...

start with 5,7,9,or start wuith 6 or start with 8

$(3*5*1*3)+(1*5*1*2)+(1*5*1*2)$

$=45+10+10$

$=65$

$P = {65 \over 840}={13 \over 168}=0,08$

OR 

Ends in 4, or ends in 6 or end in 8

$(5*5*1*1)+(4*5*1*1)+(4*5*1*1)$

$=25+20+20$

$=65$

$P = {65 \over 840}={13 \over 168}=0,08$

I've done the hard work..there are 65 permutations. They are:

5324, 6524, 7826, 9428

5326, 6528, 7924, 9524

5328, 6724, 7926, 9526

5426, 6728, 7928, 9528

5428, 6824, 8324, 9624

5624, 6924, 8326, 9628

5628, 6928, 8426, 9724

5724, 7324, 8524, 9726

5726, 7326, 8526, 9728

5728, 7328, 8624, 9824

5824, 7426, 8724, 9826

5826, 7428, 8726

5924, 7524, 8924

5926, 7526, 8926

5928, 7528, 9324

6324, 7624, 9326

6328, 7628, 9328

6428, 7824, 9426

,         ,

You have not used 5 either?

I see 3 is not used?...why would that be?

Hi guest,

So this would be the elegant way of doing it?...writing each combination out?..Thanks for your response

Hi Melody,

nope that's great thanks...so you would then have to integrate...yes, I agree about the additional info one would need to do this integration. Thanks Melody, your time is always appreciated!..stay blessed..

Hi Melody,

just a question please?

How would the sum be done If it was $F'(x)=mx^2+nx+k$ ?

Hello Melody!!,

Thank you for the explanation...yes, I am able to take everything further, it was just that step that threw me off. The answer I was looking for really, you gave to me, and it was that the y is the graph of the first derivative, which means it really is Y=mx^2+mx+k.

Okay, I fully have it now. So the formula we used was the y=m(x-x1)(x-x2)...Thank you..stay blessed!!

Ok, got it, thank you guest,...stay well

Hello again guest,

I sent response yesterday, but must have "forgotten" to actually publish my response.....

I was saying the following:

You indicated that $r={2 \over{a-1}}$

I do not get that, because this is how I see it...please advise:

$a+ar=2\Rightarrow ar=2-a\Rightarrow r={{2-a} \over a}$

How is my calculation incorrect?