Answer:
(a) 120 choices
(b) 110 choices
Step-by-step explanation:
The number of ways in which we can select k element from a group n elements is given by:

So, the number of ways in which a student can select the 7 questions from the 10 questions is calculated as:

Then each student have 120 possible choices.
On the other hand, if a student must answer at least 3 of the first 5 questions, we have the following cases:
1. A student select 3 questions from the first 5 questions and 4 questions from the last 5 questions. It means that the number of choices is given by:

2. A student select 4 questions from the first 5 questions and 3 questions from the last 5 questions. It means that the number of choices is given by:

3. A student select 5 questions from the first 5 questions and 2 questions from the last 5 questions. It means that the number of choices is given by:

So, if a student must answer at least 3 of the first 5 questions, he/she have 110 choices. It is calculated as:
50 + 50 + 10 = 110
For this case we have the following function:

To find the zeros of the function we make
and solve for "x", then:

We multiply by -1 on both sides of the equation:

We factor the equation, for this we look for two numbers that, when multiplied, result in 36 and when added, result in -13. These numbers are -9 and -4.

Thus, the factored equation is:

Therefore, the roots are:

Answer:

Answer:
9 times 4 divide by 6
Step-by-step explanation:
it might be it
Answer:
1.5 seconds
Step-by-step explanation:
i took a test with the same question
Answer:
C
Step-by-step explanation:
If it is accurate then it would have gotten the correct weight, but by going down to the thousandths it would be precise