Day 1 and Day 3 his score add up to zero.
Day 2 and Day 4 his score add up to zero.
There are, 20475 different groups are possible if the manager wants to select one group of 4 people from his 28 assistants.
<h3>What is permutation and combination?</h3>
A permutation is the number of different ways a set can be organized; order matters in permutations, but not in combinations.
We have:
A manager wants to select one group of 4 people from his 28 assistants.
The total number of groups possible = C(28, 4)

After calculating:
= 20475
Thus, there are, 20475 different groups are possible if the manager wants to select one group of 4 people from his 28 assistants.
Learn more about permutation and combination here:
brainly.com/question/2295036
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Step-by-step explanation:
Regression Equation has the firm of,
Y = aX + b
please refer to my attachment for a and b.
So prepare table with columns of Y, X sq(x),......
then work out a and b according.
Finally sub a and b into the equation Y = aX + b
15/100*x=39
x=39*100/15
x= 260 is the total number of people who were asked