The answer is: (z - 6)(z + 15)
z² + 9z - 90 = z*z + 15z - 6z - 6*15 =
= (z*z + 15z) - (6z + 6*15) =
= z(z + 15) - 6(z + 15) =
= (z - 6)(z + 15)
Answer:
Step-by-step explanation:
Answer:
x + 65 <u>< </u>108
Step-by-step explanation:
Answer:
the student should score atleast 229 to be among the top 10%.
Step-by-step explanation:
in terms of the normal distribution, and if the table that you're using calculates the area of the normal distribution from the mean to a point x, only then what we are actually finding the value 'x' at which the z-score is at 40% (the rest 50% is already skipped by the table)

after finding the the value at this z-score, we can find the value of x at which the score is in the top 10% range.
we can find the z-score either using a normal distribution table or calculator. (but be sure what area is it calculating)
looking at the table the closest value we can find is, 0.4015 at z = 1.29 ((it is above 40% because we want to be in the top 10% range)




the student should score atleast 229 to be among the top 10%.