Question

In a class of 18 students there are 11 math majors and 7 computer science majors. Fourstudents are randomly picked to prepare a demonstrate on the use of a graphingcalculator.c. How many ways can three math majors be chosen?

Answer 1

To find how many math majors can be chosen, we use combinations:

Then, if we have 11 math majors and we need to choose 3.

We got 11C3

Where the formula is given by:

$nCr=\frac{n!}{(n-r)!r!}$

Where n=11 and r=3

n is the total group and r the ways it can be chosen

Therefore:

$11C3=\frac{11!}{(11-3)!3!}=165$

Finally, we have 165 ways to choose three math majors.