I believe it’s c. I hope that this is helpful!
Answer:
The minimum level for which the battery pack will be classified as highly sought-after class is 2.42 hours
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:

What is the minimum level for which the battery pack will be classified as highly sought-after class
At least the 100-10 = 90th percentile, which is the value of X when Z has a pvalue of 0.9. So it is X when Z = 1.28.




The minimum level for which the battery pack will be classified as highly sought-after class is 2.42 hours
0.5x=6, we must find x
x=6/0.5
x=12
An open circle is used for a less than or greater than symbol. A closed circle is used for a less than or equal to, or greater than or equal to symbol.
Both of the functions have negative slopes, which we know because they point to the up and to the left.
The open circle inequality has a y-intercept at (0,2) and the closed circle inequality that is not shown by the image. However, for the closed circle inequality, we know that is must be less than or equal to, because the line goes downwards, away from the closed circle. For the open circle inequality, it must be greater than because the line goes upwards.
This leaves us with answer choices A and B. Looking at both, we can see that the only choice that fits with our observations of greater/less than or equal to, and open/closed is A.
Hope this helps!! :)