CR and Slope

Perhaps not really a Rules question, but I couldn't find a better place to put it.

My home course has 3 loops of 9 holes that are combined differently from week to week, 2 loops acting as the 18-hole course, and the last loop playing the part of a 9-hole course for new members (or 'Rabbits' as they are called over here) or members who don't have time to fit in 18 (WHAT?! Not time for 18?! Outrage!! )

Anyway. The 9-hole loop is often very empty of players, while the 18-hole course is often packed, so sometimes we decide to play the 9-loop twice for 18-holes (it can easily cut an hour off your playing time if you're a 2 ball and nobody is in front of you).

At the club, we have a handicap conversion table dictating the number of strokes given at the course, but unlike the 18-hole combinations, the 2x9 hole combinations do not have a listed CR and Slope.
Of course they exist, I just can't find them anywhere.

Since I'm working on a statistics spreadsheet to monitor my 'improvements' (yeah, I wish), I'd like to have the CR and Slope, so that I could correctly calculate the number of strokes given for any handicap.

Can I do this, based on the known CR and Slope of the 18-hole combinations?

The known data are these:

North Out - East In: CR 72,1 - Slope 126 - Par 72
West Out - East In: CR 72,9 - Slope 129 - Par 72
West Out - North In: CR 71,0 - Slope 126 - Par 72

East Out - East In: Par 72
West Out - West In: Par 72
North Out - North In: Par 72

How can I calculate CR and Slope for East/East, West/West and North/North?

__________________
//Mox
2008 bag:
Mizuno MX-500 460cc 10.5* Fujikura Tour Platform 26.3 stiff. (about to be replaced by MP-600 10,5* UST Proforce V2 stiff)
Mizuno F-50 3w 15* Fujikura Tour Platform 26.3 stiff.
Wilson Deep Red 5w 18* Graphalloy Fatshaft stiff
Cleveland HALO 3i hybrid 22* graphite regular
Mizuno MP-60e forged 5i-PW True Temper Dynamic gold R300 steel
Mizuno MP Black OX raw haze 50/6 GW, 54/9 SW, 58/10 LW
Heavy Putter B3-M
Titleist NXT Extreme

Personally, I'd set up the other combinations as Rating 72, slope 126. Three points of slope won't make much of a difference.

As for actually figuring them out, you'd need the slope and rating of each individual set of 9 - which may or may not be available at the pro shop.

So I can't base the calculation on the knowledge that East/North has a CR of 72,1 and East/West has a CR of 72,9 and from that calculate the CR of East?

I'm thinking something like the CR of East/North being comprised of half of the CR of East/East and half of the CR of North/North.

If you knew just one of the 9's, I know I could figure the rest, but I just can't seem to figure out how to get a combined 18. From the info you gave, I would suggest the East is most difficult of the 9's and North is the easiest, but I can't give you individual ratings for each 9. Ask the proshop to get this info...

I think I've cracked it ...

0.5A + 0.5B = 72.1
A(North)+B(East) = 144,2

0.5A+0.5C = 71.0
A+C(West) = 142

0.5B + 0.5C = 72.9
B+C = 145.8

C = 142 - A
A = 144.2 - B
C = 145.8 - B
C = 142 - (144,2 + B)
145.8 - B = 142 - (144.2 + B)
145.8 - 142 + 144.2 = 2B
148 = 2B
74 = B (East)

C = 145.8 - 74
C (West) = 71.8

A = 144.2 - 74
A (North)= 70.2


That makes it all work


Edited to add:

Same procedure for slope returns the full data:

North Out - East In: CR 72,1 - Slope 126 - Par 72
West Out - East In: CR 72,9 - Slope 129 - Par 72
West Out - North In: CR 71,0 - Slope 126 - Par 72

East Out - East In: CR 74,0 - Slope 129 - Par 72
West Out - West In: CR 71,8 - Slope 129 - Par 72
North Out - North In: CR 70,2 - 123 - Par 72

__________________
//Mox
2008 bag:
Mizuno MX-500 460cc 10.5* Fujikura Tour Platform 26.3 stiff. (about to be replaced by MP-600 10,5* UST Proforce V2 stiff)
Mizuno F-50 3w 15* Fujikura Tour Platform 26.3 stiff.
Wilson Deep Red 5w 18* Graphalloy Fatshaft stiff
Cleveland HALO 3i hybrid 22* graphite regular
Mizuno MP-60e forged 5i-PW True Temper Dynamic gold R300 steel
Mizuno MP Black OX raw haze 50/6 GW, 54/9 SW, 58/10 LW
Heavy Putter B3-M
Titleist NXT Extreme

I knew there was a way, but it's been too long since i used them last. Once I saw your equation, it made perfect sense. Well done.

That's some good work, Mox.

Thanks.

It's been a long time since I've worked on my maths skills. That's the problem with working with computers ... you get used to them knowing the formula already,so you won't have to!