Let 
be the random variable for the number of marks a given student receives on the exam.
10% of students obtain more than 75 marks, so
where 
follows a standard normal distribution. The critical value for an upper-tail probability of 10% is
where 
denotes the CDF of , and 
denotes the inverse CDF. We have
Similarly, because 20% of students obtain less than 40 marks, we have
so that
Then 
are such that
and we find
D) 286.7 because the number is rounded to your nearest tenth
Answer: Mark has 28 marbles while Don has 85 marbles.
Step-by-step explanation:
Let x represent the number of marbles that Mark has.
Let y represent the number of marbles that Don has.
If Don has 1 more than 3 times the number of marbles Mark has, it means that
y = 3x + 1
The total number of marbles is 113. It means that
x + y = 113- - - - - - - - - - - - 1
Substituting y = 3x + 1 into equation 1, it becomes
x + 3x + 1 = 113
4x + 1 = 113
4x = 113 - 1 = 112
x = 112/4
x = 28
y = 3x + 1 = 3 × 28 + 1
y = 85
Answer: 7,333.32 m3
Step-by-step explanation:
Hi, to answer this question we have to apply the next formula:
Volume of a cone = 1/3 x π x radius^2 x height
Replacing with the values given:
V = 1/3 π (19.3)^2 (18.8) = 7,333.32 m3
The volume of the right circular cone is 7,333.32 cubic meters.
Feel free to ask for more if needed or if you did not understand something.
