a researcher counted the hours a brand of batteries could power different devices. the data are normally distributed with a mean of 74.674.6 hours and a standard deviation of 9.19.1 hours. what percentage of devices ran on the batteries for fewer than

Respuesta :

the data are normally distributed with a mean of 74.674.6 hours and a standard deviation of 9.19.1 hours. So  10.2% of gadgets were powered by batteries for fewer than 63 hours.

Given that,

Data have a mean of 74.6 hours and a standard deviation of 9.1 hours, and they are regularly distributed.

The standard deviation is defined as ?

The standard deviation is a metric that reveals how much variance from the mean there is, including spread, dispersion, and spread. A "typical" variation from the mean is shown by the standard deviation. Because it uses the data set's original units of measurement, it is a well-liked measure of variability.

[tex]p(X\leq 63) = p(Z\leq 63-74.6/9.1)[/tex]

From standard deviation,

         [tex]p(X\leq 63) = p(Z\leq -1.279)= 0.1061[/tex]

a certain percentage of gadgets have battery life of less than 63 hours.

X= 63 hours

Percentage of devices ran on the batteries for fewer than 63 hours = 10.2%

Therefore, 10.2% of electronic devices had battery life of less than 63 hours

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