Answer:
x≤−11
Step-by-step explanation:
−99≥18x−9x
−99≥9x
−
9
99
≥x
−11≥x
x≤−11
Answer:
P(X < 80) = 0.89435.
Step-by-step explanation:
When the distribution is normal, we use 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 question, we have that:

P(X < 80)
This is the pvalue of Z when X = 80. So



has a pvalue of 0.89435.
So
P(X < 80) = 0.89435.
Two cheaper books = x
more expensive = 1.5x
so, 2.5x=150
150/2.5=x=60
therefore the more expensive book = 90
$3.29*0.65(because you're paying 65% of the original price)
$2.14(this answer is rounded up to 2.14. if you don't round, it is 2.13)