Safaricom Graduate Management Engineer interview questions

Interview process took close to 2 months. Went through 4 interviews but did not make it to the last interview. First interview was an aptitude test consisting of English and math questions, second interview was a written test consisting of GSM, transmission, system administration and programming questions, third interview was a group interview where you are divided into groups and are given a problem to tackle, afterwards, your group presents it to the interviewers (not less than 3). During the group discussion, the interviewers are present and go round checking how each member is participating in the discussions. I am a quiet, shy person and did not pass this round.