Answer:
Part 1: There are 4.7*10^21 ways to select 40 volunteers in subgroups of 10
Part 2: The research board can be chosen in 32760 ways
Step-by-step explanation:
Part 1:
The number of ways in which we can organized n elements into k groups with size n1, n2,...nk is calculate as:

So, in this case we can form 4 subgroups with 10 participants each one, replacing the values of:
- n by 40 participants
- k by 4 groups
- n1, n2, n3 and n4 by 10 participants of every subgroups
We get:

Part 2:
The number of ways in which we can choose k element for a group of n elements and the order in which they are chose matters is calculate with permutation as:

So in this case there are 4 offices in the research board, those are director, assistant director, quality control analyst and correspondent. Additionally this 4 offices are going to choose from a group of 5 doctors.
Therefore, replacing values of:
- n by 15 doctors
- k by 4 offices
We get:

Answer: x1 = 251/26, x2 = -111/26
Step-by-step explanation:
Hi!
As you can see in the figure, the point you are looking for is the intersection of two lines.
The intersection point is found solving this system of linear equations (the point must satisfy both equations):

You can solve it, for example, by the method of substitution:

Then plug x1 into equation 2, and solve for x2:

Then you use the value of x2 to get x1:

Answer:
Slope = rise / run
= -12 / 1500 (It's -12 and not 12 because a drop means it's decreasing)
= -0.008
Start with 90/240, then reduce the fraction
you can reduce by dividing each by 10 to get 9/24
reduce more from there, seeing that each number can be divided by 3
9/3 = 3
24/3 = 8
answer 3/8