In this case, we can use the z statistic to find for the proportion
of students who failed the exam. The formula for z score is given as:
t = (x – u) / s
where,
x = the sample score = 60
u = sample score mean = 82
s = standard deviation = 11
Substituting all given values into the equation:
t = (60 – 82) / 11
t = - 2
Based from the standard proportion distribution tables for
z, this corresponds to:
P = 0.0228
This means that 2.28% of the students failed the exam or
equivalent to:
failed students = (0.0228) * 85 = 1.938
<span>approximately 2 students failed the exam</span>
You have to put the parentheses like this:
In fact, you have to perform the operation inside parentheses first, and then proceed in order:
The answer is 6 x 3 x 3 = 54.
I found this by finding the surface area with 9 x 6 and then seeing that 6 x 3 x 3 gives the same answer knew that one was correct, but I'm sure there's an easier way, good luck.
