
The second one is not an equation.<span />
The answer should be 1/3=12-n
Answer:
Let X = score of final exam.
X~normal(23, 16)
(a)
percentage of score between 19 and 27
= P(19 < X < 27)
= P((19-23) / sqrt(16) < Z < (27 - 23) / sqrt(16))
= P(-1 < Z < 1)
= 1 - P(Z <= -1) - P(Z >= 1)
= 1 - P(Z >= 1) - P(Z >= 1)
= 1 - 2*P(Z >= 1)
= 1 - 2(0.1587)
= 0.6826
= 68.26%
According to Normal Distribution Table
P(Z>=1) = 1 - P(Z<1) = 1-0.8413
So the final percentage is 68.26%
In order to prove

Let's write both sides in terms of
only.
Let's start with the left hand side: we can use the formula for sum and subtraction of the sine to write

and

So, their multiplication is

So, the left hand side simplifies to

Now, on with the right hand side. We have

Now simply make this expression one fraction:

And as you can see, the two sides are equal.
Answer:
1960
Step-by-step explanation:
8 out of 10 is 80% or 0.8. 0.8 * 2540 = 1960 students.