The answer you have is good. You don't need to change anything.
13. (a-b)^2=a^2-2ab+b^2
B is the answer
14. B is the answer
( x+9)(x-3)= x^2+6x-27
15. B is the answer
(x+6)(x-5)=x^2+x-30
16. D is the answer
(x-6y)(x-4y)=x^2-10xy+24y^2
17. C is the answer
(2x+5)(3x-4)=6x^2+7x-20
18. B is the answer
(5x+7)(x-2)=5x^2-3x-14
Answer:
65.45
Step-by-step explanation:
Zscore = (x - mean) / standard deviation
x = score
Percentage below C :
D = 18% ; F = 12%
Sum = 30%
Obtain the Zscore for the proportion below D
P(Z < 0.30) = -0.524
Hence, Zscore = -0.524
Put Zscore = -0.524 in the equation :
-0.524 = (x - 72) / 12.5
-0.524 * 12.5 = x - 72
-6.55 = x - 72
-6.55 + 72 = x
x = 65.45
To receive a grade of C or better, score must be atleast 65.45
