Can someone explain probability with permutations and combinations and explain where they are applied?

combination : If the order of numbers  or  operations does not matter

Permutation : when the order of numbers matter ( common example most teachers use : a code of 4 numbers has to be in a certain order and the numbers are from 0 to 9 , how many permutation can you make if you use the number one time)

P=n!/(n-r)!

n! ( are number from 0-9 we have 10 numbers)

r is the number of digits in the code = 4

n!=10*9*8*7*6*5*4*2*1

(n-r)!=(10-4)!=6!=6*5*4*3*2*1

P=5040 ways ( if the order matter)

If the order does not matter

Combination C(n,r)=n!/(n-r)!r!

C(10,4)=(10*9*8*7*6*5*4*2*1)/[(6*5*4*3*2*1)(4*3*2*1)]

answer: city needs 2.4 inches of rainfall more to match the record of 40 inches.

step-by-step explanation:

since we have given that

total annual rainfall a city record = 40 inches

this year, total rainfall recorded = 37.6 inches

number of inches of rainfall   is needed to match the record of 40 inches is given by

hence, city needs 2.4 inches of rainfall more to match the record of 40 inches.

answer: idk

step-by-step explanation: