Respuesta :
Number of ways the second grade students can sit on the first row is 5! = 5P5
Number of ways 15 first grade students can sit in the remaining 20 seats is 20P15
Therefore, required number of ways is 5P5 * 20P15. (option B)
Number of ways 15 first grade students can sit in the remaining 20 seats is 20P15
Therefore, required number of ways is 5P5 * 20P15. (option B)