Respuesta :
Answer:
0.0336 = 3.36% probability that a teenager spends less than 90 minutes watching videos on their phone per week.
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
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.
A study indicates that teenagers spend an average of 112 minutes watching videos on their smartphones per week. Assume the distribution is normal, with a standard deviation of 12 minutes.
This means that [tex]\mu = 112, \sigma = 12[/tex]
What is the probability that a teenager spends less than 90 minutes watching videos on their phone per week?
This is the p-value of Z when X = 90. So
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]Z = \frac{90 - 112}{12}[/tex]
[tex]Z = -1.83[/tex]
[tex]Z = -1.83[/tex] has a p-value of 0.0336
0.0336 = 3.36% probability that a teenager spends less than 90 minutes watching videos on their phone per week.
