Answer:
0.8808
Step-by-step explanation:
The objective is to calculate the probability of:
P(-1.20 ≤ z ≤ 2.64)
i.e. the probability that is the area between two z-values.
Thus;
P(-1.20 ≤ z ≤ 2.64) = P(z ≤ 2.64) - P( z ≤ 1.20)
From z table;
P(-1.20 ≤ z ≤ 2.64) = 0.9959 - 0.1151
P(-1.20 ≤ z ≤ 2.64) = 0.8808
We can see the shaded area under the standard normal curve from the image attached below.
To solve/simplify this all you have to do is group like terms (the x^2's with each other, the x's with each other, and the normal numbers, -8)
14x^2-8+5x-6x^2+2x
group the x^2 (add 14x^2 to -6x^2)
8x^2-8+5x+2x
group the x's together (add 5x and 2x together)
8x^2+7x-8
Your answer will be d) 8x^2+7x-8
z equals -1 because 8 time negative one equals negative 8 plus 8 equals 0