[R] predicting values into the future

[Felipe Carrillo]

Hi:
I have usually used the GROWTH() excel function to do this but now want to see if I can do this with R.
I want to predict values into the future, possibly with the predict.arima Function. 
I have the following weekly fish weight averages:

weight <- c("2.1","2.4","2.8","3.6","4.1","5.2","6.3")
week   <- c("1","2","3","4","5","6","7")

I would like to predict what the weight will be by week 10 based on my weight values and make a line plot of all the weights(including the predicted values). I have two questions:
1- Should the predicted values be linear or exponential?
2- Is the predict.arima function appropriate to do this?
Thanks in advance. 


Felipe D. Carrillo  
Supervisory Fishery Biologist  
Department of the Interior  
US Fish & Wildlife Service  
California, USA