How to factor out expressions
1 answer:
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*see attachment for the dot plot being referred to
Answer:
The data is symmetric and shows that he typically sent about 6 to 8 text messages per day
Step-by-step explanation:
The distribution of the data set on a dot plot can be said to be symmetric when most of the data points in the data are located or are concentrated at the center of the dot plot.
As we can observe from the given dot plot in the attachment, it shows that 6 to 8 text messages per day have more frequencies and are just right at the center of the dot plot. This shows the data is symmetric.
This also shows that Reza dents averagely 6 - 8 text messages per day. Reza can be said to have typically sent 6 - 8 text messages per day.
The rest statements about the dot plot are untrue.
A statistics student would like to estimate the average age of students at her college. she would like to be 85% confident that her estimate includes the actual college population mean
It means confidence level is 0.85.
After taking survey the estimate of population standard deviation is found as 4.5 years. The given margin of error is 0.5 years
The sample size is obtained using formula
n=
Where std = standard deviation
alpha = 1 -c = 1-0.85 = 0.15
z(α/2) = z(0.15/2) = z(0.075)
It is the critical value of z such that area above z and below -z is 0.075
Use z score table to find the probability exactly or very close to 0.075 and note the corresponding z score value.
In z score table there is no accurate 0.075 probability value. The close value is 0.0749 which corresponds to z score -1.44
For calculation we take positive z score value.
So we get z(α/2) =1.44
Using all the given values into formula
n = [(1.44 * 4.5) / 0.5]^2
n = 167.96
Rounding it to nearest integer we get n=168
The number of people need to surveyed is n=168
