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:
57°
Step-by-step explanation:
Let's assume the measurement of the second angle is x.
so, following the problem
(2x + 9) + x = 180
2x + x = 3x
=> 3x + 9 = 180
=> 3x = 180 - 9
3x = 171
x = 171/3
x = 57°
57° is the smallest angle
Answer:
im gussing sorry if its wrong :(
Step-by-step explanation:
1=a
2=d
3=b
4=c
The answer is Y=-2/5x+1 :)