# Tagged with combinatorics …

## #math trivia solution: What are the chances that a class of 20 has 10 girls and 10 boys?

#math trivia: If girls and boys are equally represented in the school population, what are the chances that a class of 20 has 10 of each? — Burt Kaliski Jr. (@modulomathy) October 16, 2012 This is another combinatorics problem. Each seat in the class will be occupied either by a girl or a boy. The … Continue reading

## #math trivia solution: The principal chooses one student from each of 5 classes …

#math trivia: The principal chooses one student from each of 5 classes of 20 for a project team. How many different “rosters” are possible? — Burt Kaliski Jr. (@modulomathy) October 1, 2012 The number of possible rosters is 3.2 million. This assumes that it doesn’t matter in what order the students are chosen for the … Continue reading

## #math trivia solution: The five classes eat lunch at separate times …

#math trivia: The five classes eat lunch at separate times. Every day their times are in a different order. How long can this go on? — Burt Kaliski Jr. (@modulomathy) September 17, 2012 There are 5*4*3*2*1 = 120 different possible orders in which the five classes can eat lunch, so this can go on for … Continue reading

## #math trivia solution: Two friends got in the same class …

#math trivia: The two friends got in the same class. Seats are assigned randomly, 4 rows of 5. What are the chances that they sit together? — Burt Kaliski Jr. (@modulomathy) September 3, 2012 The chances that the two friends are seated next to each other is 8/95.  This can be calculated as follows: The … Continue reading

## #math trivia solution: 100 students are assigned randomly …

#math trivia: 100 students are assigned randomly to 5 classes of equal size. What are the chances that two friends get in the same class? — Burt Kaliski Jr. (@modulomathy) August 28, 2012 The chances that two friends get in the same class is 19 out of 99. If the classes didn’t have to be … Continue reading