Question
In: Statistics and Probability
Question 1: A survey was conducted to estimate the proportion of car drivers who use seatbelts...
Question 1: A survey was conducted to estimate the proportion of car drivers who use seatbelts while driving. Of the 1500 drivers sampled, 520 drivers said, they always use seatbelt while driving.
- Estimate the value of the population proportion.
- Compute the standard error of the proportion.
- Develop a 99% confidence interval for the population
proportion.
- Interpret your findings
Question 2: The registrar wants to estimate the arithmetic mean of grade point average (GPA) of all graduating seniors during the past 10 years is to be estimated. GPAs range between 3.0 and 5.0. The mean GPA is to be estimated within plus or minus 0.05 of the population mean. The standard deviation is estimated to be 0.389. Use the 99 percent level of confidence. How many transcripts should the registrar study?
Solutions
Expert Solution
Q 1. ) If 1500 were samples and 520 said yes then the sample proportion would be
The Confidence interval is calculated as
={0.3153, 0.3787}
Where,
is the Standard error
The Z score at 99 % confidence interval is 2.58 Computed using Z table shown below
Interpretation :
we can be 99 % confident that the population proportion lies within the calculated interval.
Q 2) .
The Minimum sample is calculated as
Where Margin of error, E= 0.05
Standard deviation =0.389
and Z score at 99 % confidence level is 2.58
Z table:
orchestra answered 2 years agoRelated Solutions
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