Tried to do some arithmetics with rand 5 to get to rand 7. He told me I'm not in the right direction. Then I tried to play with the array structure in order to use the rand 5 statistic to get to rand 7. Again he said I'm not in the wrong direction and we stopped. After the interview I checked for the solution. Apperently, both times I was in the right direction and was strayed by the interviewer.