JAMB - Mathematics (2013 - No. 29)
In how many ways can 3 seats be occupied if 5 people are willing to sit?
60
20
5
120
설명
5 people can take 3 places in;
5P3 ways, = \(\frac{5!}{(5 - 3)!}\) = \(\frac{5!}{2!}\)
= \(\frac{5 \times 4 \times 3 \times 2!}{2!}\)
= 5 x 4 x 3
= 60 ways
5P3 ways, = \(\frac{5!}{(5 - 3)!}\) = \(\frac{5!}{2!}\)
= \(\frac{5 \times 4 \times 3 \times 2!}{2!}\)
= 5 x 4 x 3
= 60 ways