Answer:
D.
Step-by-step explanation:
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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The answer is 7 cups of water are needed for 21 cups of flour.
Shown work:
1 cup of water=3 cups of flours
? Cup of water=21 cups of flours
21 divided 3=7
1 multiply by 7= 7 cups of water needed