Help with forecasting future values based on a current value?

[Jacques Brun]

Consider the following spreadsheet
A B C D E F G H I J
1 0 1 2 3 4 5 6 Target
2 0 150 220 1500
3
4 End Hour Forecast: 1250
5 Level to reach target: 282.5

formula in F4 =SUM(A2:G2)+(7-COUNT(A2:G2))*INDEX
(A2:G2,1,COUNT(A2:G2))
formula in F5 =IF(COUNT(A2:G2)=7,"Too late",(H2-SUM
(A2:G2))/(7-COUNT(A2:G2)))

B2:G2 contains the production of the hour so far (here
production known for the first 12 minutes and still
blank for the rest of the hour)
H2 contains the production target (here 1500)
A2 must be 0 and corresponds to production of a dummy
period to avoid errors in formulas

Formula in F4 :
= SUM(A2:G2) = production of past segments (non zero)
+ (7-count(A2:G2) number of remaining segments in the hour
* Index(A2:G2,1,count(A2:G2)) production of last segment
Gives the hour forecast if production remains at current
level

Formula in F5
H2-sum(A2:G2) is what to produce to reach the target
(7-COUNT(A2:G2))) is the number of remaining segments
the ratio of above is the required level to reach the
target.
the IF is to cope with the complete hour situation
and avoid a division by Zero in this case the answer
is "too late"

Hope this helps...

-----Original Message-----
I look at electrical generation (kWhâ?Ts) in 10 minute

segments, 6 segments making up the complete hour. During
any of these segments I would like to be able to forecast
what the total would be at the end of the hour if we
remained at the current production level. Or what we
would need to increase production to, to meet a target
value at the hour end.