Question

Cathy and iris are planning trips to nine countries this year. There are 13 countries they would like to visit. They are deciding which countries to skip,how many ways are there?

Answer 1

Cathy and Iris have 259,459,200 ways to skip countries.

Data;

• Number of countries they are planning to visit = 9
• Number of countries they would like to visit = 13

Combination

To solve this problem, we would have to use a mathematical procedure known as combination.

Let us calculate the number of countries that would have to skip.

$13 - 9 = 4$

To decide which country they have to skip, it would be 4 out of 13.

$x = ^1^3C_4 = \frac{13!}{4!}$

Let's solve this

$\frac{13!}{4!} = \frac{13*12*11*10*9*8*7*6*5*4*3*2*1}{4*3*2*1}\\ \frac{13!}{4!} = 13*12*11*10*9*8*7*6*5 = 259459200 ways$

Cathy and Iris have 259,459,200 ways to skip countries.

Learn more on combination here;

brainly.com/question/12468032