There are 100 students at a school and three dormitories A, B, and C with capacities of 25, 35, and 40, respectively.

Required:
a. How many ways are there to fill up the dormitories?
b. Suppose that, of the 100 students, 50 are men and 50 arewomen and that A is an all-men's dorm, B is an all-women's dorm andC is co-ed. How many ways are there to fill thedormitories?

Respuesta :

Answer:

a

[tex]N = 7.0 *10^{44} \ Ways [/tex]

b

[tex]U  = 2.85 *10^{26}\  ways [/tex]

Step-by-step explanation:

From the question we are told that

   The number of students are  n =  100

    The number of dormitories  is  k =  3

    The capacity of the first dormitory is  A =  25

     The capacity of the second dormitory is  B =  35

      The capacity of the third dormitory is  c =  40

Generally the number of way to fill the dormitory up is mathematically represented as

      [tex]N  =  \frac{n!}{A! B!C!}[/tex]

=>   [tex]N  =  \frac{100!}{25! 35! 40!}[/tex]

Here ! stands for factorial, so we will be making use of the factorial functionality in our calculators to  evaluated the above equation

=>   [tex]N  =  \frac{100!}{25! 35! 40!}[/tex]

[tex]N = \frac{9.332622* 10^{157}}{[1.551121* 10^{25}]* [1.0333148* 10^{40}] * [8.1591528*10^{47}]}[/tex]

[tex]N = 7.0 *10^{44} \ Ways [/tex]

From the question we are told that there are 50 men and  50  women and

     A is  all-men's dorm and  B is all-women's dorm while C is co-ed

So

When A is filled , the number of men that will be remaining to fill dorm C is  50-25 = 25

While when B is filled the number of women that will be remaining to fill dorm C is   50-35 = 15

Generally the number of ways there to fill the dormitories is equivalent to the number of ways of selecting the 25 men and 35 women to fill dormitory A and B plus one more way which is filling dorm C with the remaining students this is  mathematically represented as  

       [tex]U  =  ^{50}C_{35} * ^{50}C_{25}  +  1[/tex]

Here C stands for combination hence we will be making use of the combination functionality in our calculators

     [tex]U  = 2.250829575* ^{12}  * 1.264106064 * 10^{14} +  1[/tex]

=>    [tex]U  = 2.85 *10^{26}\  ways [/tex]