Factor 3125 -> 5^5
so
5c^4-3125
=5c^4-5^5
=5(c^4-5^4)
=5(c^2+5^2)(c^2-5^2)
=5(c^2+5^2)(c+5)(c-5)
I got 6 for my answer, but I'm not 100% sure if I'm right.
6(2x-11)+15=21
12x-66+15=21
12x-51=21
+51 +51
12x=72
----- ----
12 12
x=6
Answer:
The passing score is 645.2
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:

If the board wants to set the passing score so that only the best 10% of all applicants pass, what is the passing score?
This is the value of X when Z has a pvalue of 1-0.1 = 0.9. So it is X when Z = 1.28.




The passing score is 645.2