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:
H₀: µ ≤ $8,500; H₁: µ > $8,500
z= +1.645
Step-by-step explanation:
From the given problem As average cost of tuition and room and board at a small private liberal is less than the financial administrator As hypothesis is true.
As standard deviation is $ 1,200
α = 0.05
H₀: µ ≤ $8,500
if the null hypothesis is true then value for critical z is +1.645.
14/38 simplified would be 7/19
