Aschool bus has 25 seats, with 5 rows of 5 seats. 15 students from the first grade and 5 students from the second grade travel in the bus. how many ways can the students be seated if all of the second-grade students occupy the first row?
a. 25p20
b. 5p5 × 20p15
c. 5c5 × 25c14
d. 5p5 × 15p15
e. 5p5 × 25c15

The correct option is b.

Step-by-step explanation:

It is given that the school bus has 25 seats, with 5 rows of 5 seats.

The number of students from the first grade is 15 and the number students from the second grade is 5.

The formula to arrange r items in n places is

The number of seats in first row is 5 and the number students from the second grade is 5. So, the total number of arrangement is

The number of seats except first row is 20 and the number students from the first grade is 15. So, the total number of arrangement is

The total number of ways the students can be seated if all of the second-grade students occupy the first row is

Therefore the correct option is b.

i think it would be 42cm