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:
(16+25)×47
Step-by-step explanation:
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Im not 100% sure but im pretty sure you are right brother! God bless...Good luck!
I think it's none because that should be communitive and that's not there so.
