John, Peter, Rudolf, Susie and Tony decide to set some questions for the Schools Mathematical Challenge.
John thinks up twenty-five questions and circulates them to the others. Peter, not wishing to be outdone, then sends twenty-six questions. Rudolf decides he had better get cracking and produces thirty questions. Susie sets to and comes up with thirty-nine posers, only to be beaten by Tony who produces fifty five stunning problems.
If each person takes half as long as the previous person to set each question, and Rudolf takes one hour to set all his questions, then what is the total time spent settting questions?
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.
This problem is taken from the UKMT Mathematical Challenges.