The first question can be any one of the 10. For each of these . . .
The second question can be any one of the remaining 9. For each of these . . .
The third question can be any one of the remaining 8.
Total number of ways to choose 3 questions = (10 x 9 x 8) = 720 ways.
But the same 3 questions can be chosen in any one of 6 sequences.
So the number of different sets of 3 questions is only 720/6 = 120 .
100,000,000 ways
This is 6! {factorial} = 6 x 5 x 4 x 3 x 2 x 1 = 720. The way this works: take student A, who can choose any of the 6 desks, then for each of those 6 choices that student A makes, student B has 5 desks to choose from, after that choice has been made, student C has 4 desks to choose from, ... until the last student has only one to choose from.
To find the number of ways to have one answer true and three answers false in a set of four true or false questions, we can use combinations. Specifically, we need to choose 1 question to be true from the 4 available questions, which can be calculated using the combination formula ( \binom{n}{k} ), where ( n ) is the total number of questions and ( k ) is the number of questions to choose. Thus, the number of ways to choose 1 true answer from 4 questions is ( \binom{4}{1} = 4 ). Therefore, there are 4 different ways to have one true answer and three false answers.
If he must answer the last question, he effectively needs to select 6 from 10. This can be done in 10C6 = 10*9*8*7/(4*3*2*1) = 210 ways.
Nine
330 ways. Once we know he must answer the last question, the issue is really one of choosing 4 questions from the first 11 questions on the exam. There are 11 ways to choose the first question, 10 ways to choose the second, 9 ways to choose the third, and 8 ways to choose the fourth, so that would be 11*10*9*8... but the order of the questions doesn't matter. So we divide by the number of ways to rearrange the 4 questions (4*3*2*1=24), to get 330.
they can complete this exam 300 ways
100,000,000 ways
Two books are compulsory, so the student really wants to know how many ways he can pick 3 out of 7. That is 35.
Five (5) multiply by (*) Four (4) = Twenty (20).
16
Combination; number of ways = 21
The first student has 3 chairs to choose from. Once he has mad the choice, the second student has 2 chairs to choose from. And the last student only has 1 choice, so 3 x 2 x 1 = 6 ways.Here are the six ways. For ease, call the students A, B, and C:ABCACBBACBCACABCBA
This is 6! {factorial} = 6 x 5 x 4 x 3 x 2 x 1 = 720. The way this works: take student A, who can choose any of the 6 desks, then for each of those 6 choices that student A makes, student B has 5 desks to choose from, after that choice has been made, student C has 4 desks to choose from, ... until the last student has only one to choose from.
If he must answer the last question, he effectively needs to select 6 from 10. This can be done in 10C6 = 10*9*8*7/(4*3*2*1) = 210 ways.
An essay question can benefit a student in two ways: It can encourage the student to think more clearly, as to express the idea in writing, and hence it can also sharpen the student's writing skills.
144 ways