Answer:
Option: b is correct.
b. C(10,7)
Step-by-step explanation:
The formula for C(n,k) is evaluated as:
![C(n,k)=\dfrac{n!}{k!\times (n-k)!}](https://tex.z-dn.net/?f=C%28n%2Ck%29%3D%5Cdfrac%7Bn%21%7D%7Bk%21%5Ctimes%20%28n-k%29%21%7D)
Also The formula for P(n,k) is evaluated as:
![C(n,k)=\dfrac{n!}{(n-k)!}](https://tex.z-dn.net/?f=C%28n%2Ck%29%3D%5Cdfrac%7Bn%21%7D%7B%28n-k%29%21%7D)
![C(10,3)=\dfrac{10!}{3!\times (10-3)!}\\\\C(10,3)=\dfrac{10!}{3\times 7!}\\\\C(10,3)=120](https://tex.z-dn.net/?f=C%2810%2C3%29%3D%5Cdfrac%7B10%21%7D%7B3%21%5Ctimes%20%2810-3%29%21%7D%5C%5C%5C%5CC%2810%2C3%29%3D%5Cdfrac%7B10%21%7D%7B3%5Ctimes%207%21%7D%5C%5C%5C%5CC%2810%2C3%29%3D120)
a)
![C(3,10)=\dfrac{3!}{10!\times (3-10)!}\\\\C(3,10)=\dfrac{3!}{10!\times (-7)!}](https://tex.z-dn.net/?f=C%283%2C10%29%3D%5Cdfrac%7B3%21%7D%7B10%21%5Ctimes%20%283-10%29%21%7D%5C%5C%5C%5CC%283%2C10%29%3D%5Cdfrac%7B3%21%7D%7B10%21%5Ctimes%20%28-7%29%21%7D)
and e know the factorial of negative number does not exist.
so, this is not possible.
Hence, option a is incorrect.
b)
C(10,7)
![C(10,7)=\dfrac{10!}{7!\times (10-7)!}\\\\C(10,7)=\dfrac{10!}{7!\times 3!}\\\\C(10,7)=120](https://tex.z-dn.net/?f=C%2810%2C7%29%3D%5Cdfrac%7B10%21%7D%7B7%21%5Ctimes%20%2810-7%29%21%7D%5C%5C%5C%5CC%2810%2C7%29%3D%5Cdfrac%7B10%21%7D%7B7%21%5Ctimes%203%21%7D%5C%5C%5C%5CC%2810%2C7%29%3D120)
Hence, option b is correct.
c)
P(10,3)
![P(10,3)=\dfrac{10!}{(10-3)!}\\\\P(10,3)=\dfrac{10!}{7!}\\\\P(10,3)=720](https://tex.z-dn.net/?f=P%2810%2C3%29%3D%5Cdfrac%7B10%21%7D%7B%2810-3%29%21%7D%5C%5C%5C%5CP%2810%2C3%29%3D%5Cdfrac%7B10%21%7D%7B7%21%7D%5C%5C%5C%5CP%2810%2C3%29%3D720)
Hence, option c is incorrect.
Hence, C(10,7) is equal to C(10,3).
Hence, option b is correct.