Question

An agriculture researcher wants to test the effect of nine soil additives by adding four at a time to different rows of the same plant. How many different combinations can be tested?

Answer 1

Answer:

126 combinations can be tested.

Step-by-step explanation:

An agriculture researcher wants to test the effect of nine soil additives by adding four at a time to different rows.

We have to find the combination which can be tested.

Combinations formed can be written as  $^{9}C_{4}$

$^{9}C_{4}$ = $\frac{9!}{(4!)(9-4)!}$

      = $\frac{9!}{4!5!}=\frac{9\times 8\times 7\times 6\times 5!}{(4\times 3\times 2\times 1)\times 5!}$

      = $\frac{9\times 8\times 7\times 6}{4\times 3\times 2\times 1}$ = $\frac{3024}{24}=126$

therefore, 126 combinations can be tested.

Answer 2

I believe its 126 let me know if its right ^_^