Answer:
x≥9
Step-by-step explanation:
Pretend the Less than or equal to sign is just an equals sign
-7x+7=-56 Solve:
-7x=-56-7
-7x=-63
For the last step, if you divide a negative number, the Sign switches. So not the sign is greater than or equal to.
x>=9
2,000
10,000 divided by 5 = 2,000
374 = 33
272 = x
374/33 = 272/x
x=(33*272)/374=24 minutes
Answer:
A customer who sends 78 messages per day would be at 99.38th percentile.
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean
and standard deviation
, the z-score 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 p-value, we get the probability that the value of the measure is greater than X.
Average of 48 texts per day with a standard deviation of 12.
This means that 
a. A customer who sends 78 messages per day would correspond to what percentile?
The percentile is the p-value of Z when X = 78. So



has a p-value of 0.9938.
0.9938*100% = 99.38%.
A customer who sends 78 messages per day would be at 99.38th percentile.