Hi,
is it possible to give his results to a participant. I mean for each question in each group there is a score, I would like to give them there score by group and give them a text with some feedbacks
Than for your help

Of course you can do that.
Use ExpressionScript (in versions before 4.x. called Expression Manager) to calculate the score.
Create either a question of type "text display" to show the results to the participant
or show it in the end message, or you might use the plugin pdfReport to create a pdf that your participant download.

You have a lot of options, but you have to explain a bit more.

Joffm

thank you!

to give you more details, it's a personnality test with five factors (groups) each containing 6 questions. I use scale for each question (1 to 5, 1 meaning "not all", 5 "totally me"). So I need to give them the mean (or sum, it's ok too) on each group in order the participants knows weither he/she scores high or low on the group, which group is the more important for him/her and hence refer to the description of his/her personnality type according to the score

This can easily be done with Expression Manager/Script as Joffm has mentioned. If you want to give them scores per group, I would create a equation question per group and calculate their score within that equation question via expression script and store it there.

I assume that the "report" will be given only at the end. There you can use text display questions also with Expression script showing their results per group and taylor a report based on the respondents results.