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
Answer: Choice C) -11
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Explanation:
The first equation given is y = 3 - 1/2x
In other words, y is the same as 3 - 1/2x.
We can replace y in the second equation with 3 - 1/2x
This is known as substitution (think of a substitute teacher who is a temporary replacement for your teacher)
Doing this leads to...
3x+4y = 1
3x+4*y = 1
3x+4*( y ) = 1
3x+4*( 3 - 1/2x ) = 1 <<--- y has been replaced with 3-1/2x
3x+4*(3) +4*(-1/2x) = 1
3x+12-2x = 1
3x-2x+12 = 1
x+12 = 1
x+12-12 = 1-12 <<-- subtracting 12 from both sides
x = -11
Which is why the answer is choice C) -11
Answer: $1980
Step-by-step explanation:
Well, based off of the question being asked, I assume that you will need to pay $11 for 90 square footage of tiling, and then the same for the other square footage of tiling. Therefore your answer will be $1980. If you are looking for the equation, it is (<em>11x90)=990 (990)2 = 1980</em>
you do not need to multiply 11 by 90 again because you already know the answer.
19.20 divided by 7.5
= 2.56
2.56 is your answer.
we are given with two dice and that we are asked in the problem to find the probability of the following:
a. sum at least 4b. sum at least 6
THe sample space of this problem is
{11, 12, 13, 14, 15, 16, 21,22, 23,24,25,26,31,32,33,34,35,36,41,42,43,44,45,46,51,52,53,54,55,56,61,62,63,64,65,66} a total of 36.a. 33/36 = 11/12b.11/36
