Question

the marks for a test are normally distributed with mean,A and standard deviation,B.if 8% of student obtain more than 75 marks and 20% less than 40 marks.find mean and standard deviation

Answer 1

will medal

Answer 2

Sorry Ma'am I am weak at mathematics. Plz don't msg me Mathematics Question

Answer 3

Cool problem. I think maybe I've never seen one like this, before. I'll do most of it. One for free.

8% of students achieved above 75.
Z-score for 8% in the right tail is 1.4050
20% of students achieved below 40.
Z-score for 20% in the left tail is -0.8415

Construct each piece:

\(1.405 = \dfrac{75-\mu}{\sigma}\)

\(-0.8415 = \dfrac{40-\mu}{\sigma}\)

Solve the system of two equations with two unknowns.