Scores on a test have a normal distribution with mean 20. 95% of the test scores are between 13 and 27. What is the
standard deviation of test scores?

answer: i think it is (1,-2)

go on the tube you might find some information there

option (b) is correct

step-by-step explanation:

to find the solution of this system, we need to convert it into reduced row-echelon form. we have,

after applying row operations r2 -> r2/2 and r3 -> r3/3, we get,