# math

posted by .

Is this the right way to answer this question?
A physics exam consists of 9 multiple-choice questions and 6 open-ended problems in which all work must be shown. If an examinee must answer 7 of the multiple-choice questions and 3 of the open-ended problems, in how many ways can the questions and problems be chosen?
(9x8x7x6x5x4x3)x (6x5x4) = 21772800

• math -

The number of possibilities is nCk, or n choose k.

nCk = n! / (k! (n-k)!)

For example, the number of possibilities for the multiple choice questions is 9C7.

There are 2 types of questions - multiply the number of possibilities for each question.

• math -

I tried that and it doesn't seem to add up.
n! = 9x8x7x6x5x4x3x2 / (k= 7x6x5x4x3x2(2) = 362880/5040(2)=362880/10080 = 36 there seems to be more possibilities than that

• math -

For the multiple choice questions, the examinee is choosing 7 out of 9 questions. There are not so many ways you can choose 7 of those 9 - remember order does not matter.

Also, after you compute the 6C3 for the open ended, and multiply them, you end up with 720 possibilities total.

• math -

Thank you thank you!! I understand now!

## Similar Questions

1. ### AP stuff

"Come to... classroom after school (the possible dates will be announced later in April). There you will naswer 20 multiple choice questions based on the text, as well as AP style multiple choice questions. You will also answer 2 openended …
2. ### math

Part A of your history test has 15 multiple choice questions. Each question has four choices. Part B has 10 true/false questions. How many ways are there to answer the 15 multiple choice questions?
3. ### Stats

An instructor gives a test with 20 multiple choice questions. There are 4 responses per questions and only one choice correct. The test also has 30 True/False questions. Determine the probability a student randomly guessing on all …
4. ### Math

A physics exam consists of 9 multiple-choice questions and 6 open-ended problems in which all work must be shown. If an examinee must answer 5 of the multiple-choice questions and 2 of the open-ended problems, in how many ways can …
5. ### MATH

A physics exam consists of 9 multiple choice questions and 6 open-ended problems in which all work must be shown.If an examinee must answer 6 of the multiple- choice questions and 3 of the open-ended problems, in how many ways can …
6. ### SOLVE -MATH

A physics exam consists of 9 multiple choice questions and 6 open-ended problems in which all work must be shown.If an examinee must answer 6 of the multiple- choice questions and 3 of the open-ended problems, in how many ways can …
7. ### Algebra

An algebra teacher is writing a test. There will be two types of questions: multiple-choice and open-ended. The multiple-choice questions take 3 minutes to complete and the open-ended questions take 12 minutes to complete. There must …
8. ### Statistical concept 68-95-99.7

1. A student taking a midterm exam in Ancient History comes to two questions pertaining to a lecture that he missed, and so he decides to take a random guess on both questions. One question is true-false and the other is multiple choice …
9. ### Stat HW for.

1. A student taking a midterm exam in Ancient History comes to two questions pertaining to a lecture that he missed, and so he decides to take a random guess on both questions. One question is true-false and the other is multiple choice …
10. ### MATH

A quiz consists of 90 multiple-choice questions, each with 4 possible answers (A, B, C and D). For someone who makes random guesses for all of the answers, find the probability of getting A as right answer. A is the correct answer …

More Similar Questions