A civil air patrol unit of fifteen members includes two two officers. in how many ways can four members be selected for a search and rescue mission such that at least one officer is included?

1365 ways

Explanation: this is a combination questions

n = 15

r = 4

Solution

15C⁴

= n! / r! (n-r)!

= 15! / 4! ( 15-4)!

= 15! / 4! (11)!

= 1.308 *10¹² / 24(39916800)

= 1365 ways

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.