I assume you're asking for the scale? It would be 4:64, which simplifies to 1:16.
From all those aforementioned, the true statement is: Thanh’s grade is 2.5 standard deviations below the mean of the test grades.
Can you please attach the photo?
When writing the equation keep in mind that 7 + x is said as a term that is squared so it has to be squared while it's still together; (7 + x)².
