. A system may become infected by some spyware through the internet or e-mail. Seventy percent of the time the spyware arrives v
1 answer:
Answer:
This spyware is detected 66% of the time.
Step-by-step explanation:
We have these following percentages:
70% of the time, the spyware arrives via the internet, and in this case, is detected 60% of the time.
30% of the time, the spyware arrives via e-mail, and in this case, is detected 80% of the time.
What percentage of times is this spyware detected
Sum of 60% of 70%(arrived via spyware, detecte) and 80% of 30%(arrive via e-mail, detected). So
This spyware is detected 66% of the time.
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Answer:
And using a calculator, excel ir the normal standard table we have that:
And we can calculate the probability like this:Step-by-step explanation:
A random sample of 36 observations has been drawn from a normal distribution with mean 50 and standard deviation 12. Find the probability that the sample mean is in the interval 47<=X<53. Is the assumption of normality important. Why?
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the variable of interest of a population, and for this case we know the distribution for X is given by:
Where and
Since the distribution for X is normal then we know that the distribution for the sample mean is given by:
We can find the probability required like this:
And using a calculator, excel ir the normal standard table we have that:
And we can calculate the probability like this: