42 - (-25) = 42 + 27 = 69
33 - (-77) = 33 + 77 = 110
44 + (-18) = 44 - 18 = 26
There are 600 students including the seventh and eighth graders at the party.
This problem uses the concept of percentages to define the conditions that are laid in front of us.
Let the original number of students be S , and the number of seventh graders be = 0.60S
We know that percent is used to convey the mathematical term of a fraction multiplied by 100.
Total students after 20 eighth graders arrive = S + 20
And we have that
Number of seventh graders / total number of students = 58%
.60S / [ S + 20 ] = .58 we multiply both sides by S + 20
0.60S =0 .58 [ S + 20]
.60S = .58S + 11.6 we subtract 0.58S from both the sides
0.02S = 11.6 we divide both the sides by .02
S = 11/6 / 0.02 = 580
So the total number of students = 580 + 20 = 600 .
Hence there are 600 students at the party at that time.
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Answer: a) 
b) 
c) 
Step-by-step explanation:
Given : Number of students : 11
Number of faculty members : 13
Total persons : 
Total number of ways to structure a jury of six people from a group of 24 people :-

a) Number of ways of selecting a jury of all students :-

Then , the probability of selecting a jury of all students :-

b) Number of ways of selecting a jury of all faculty :-

Then , the probability of selecting a jury of all students :-

c) Number of ways of selecting a jury of two students and four faculty :-

Then , the probability of selecting a jury of all students :-

Answer:
c. how late it is in the evening is a function of the length of time the shutter needs to stay open.