There are 9 students running for 4 openings on the student council. only students who are running for election can be elected; no write-in candidates are allowed. an elected student can only hold one position at a time. use pascal’s triangle to find the number of different ways 4 students can be elected from the group of 9 candidates.

White shapes and black shapes are used in a game. some of the shapes are circles. while the rest are squares. the ratio of the number of white shapes to the number of black shapes is 5: 11. the ratio of the number of white cicrles to the number of white squares is 3: 7. the ratio of the number of black circles to the number of black squres is 3: 8. work out what fraction of all the shapes are circles.