1.
Let's assume that the 3 candidates are named A, B, and C.
If all 70 students vote, there are a total of 70 choices for the first vote, 69 choices for the second vote, and 68 choices for the third vote, since each student can only vote once and cannot vote for themselves. Therefore, the total number of possible vote counts is:
70 x 69 x 68 = 328,920
Now, if some students do not vote, the total number of possible vote counts will decrease. Let's consider some scenarios:
If one student does not vote: There are 70 choices for who does not vote. For the remaining 69 students, there are 328,920 possible vote counts. Therefore, the total number of possible vote counts when one student does not vote is:
70 x 328,920 = 23,064,400
If two students do not vote: There are (70 choose 2) = 2,415 ways to choose two students out of 70 who do not vote. For the remaining 68 students, there are 328,920 possible vote counts. Therefore, the total number of possible vote counts when two students do not vote is:
2,415 x 328,920 = 793,556,800
If three students do not vote: There is only one way to choose three students out of 70 who do not vote. For the remaining 67 students, there are 328,920 possible vote counts. Therefore, the total number of possible vote counts when three students do not vote is:
1 x 328,920 = 328,920
In summary, the total number of possible vote counts when some students do not vote is:
23,064,400 + 793,556,800 + 328,920 = 817,950,120
2.
We can use a stars and bars approach to solve this problem. We need to distribute 7 pieces of taffy and 8 pieces of licorice to 5 kids such that each kid receives exactly 3 pieces of candy.
Let's represent the distribution using 5 variables: x1, x2, x3, x4, x5, where xi represents the number of pieces of candy given to the ith kid. Since each kid must receive 3 pieces of candy, we can subtract 3 from each xi to simplify the problem.
So, we need to distribute (7-3x5) = 2 pieces of taffy and (8-3x5) = -7 pieces of licorice among 5 kids, without any restriction on the number of pieces each kid gets. Notice that we have negative pieces of licorice, but this simply means that some kids will get no licorice at all.
Using the stars and bars formula, the number of ways to distribute 2 pieces of taffy and -7 pieces of licorice among 5 kids is:
C(2+5-1, 5-1) * C(-7+5-1, 5-1) = C(6, 4) * C(-3, 4)
where C(n, k) represents the number of ways to choose k items out of n.
Since C(-3, 4) is not defined, we need to use a different formula for negative values. The formula is:
C(-n+k-1, k-1) = C(n+k-1, k-1)
Using this formula, we get:
C(6, 4) * C(3+4-1, 4-1) = C(6, 4) * C(6, 3)
= 15 * 20
= 300
Therefore, there are 300 ways to distribute 7 pieces of identical taffy and 8 pieces of identical licorice to 5 kids such that each kid receives exactly 3 pieces of candy.