Question

In: Statistics and Probability

In a recent poll, 160 people were asked if they liked dogs, and 55% said they...

In a recent poll, 160 people were asked if they liked dogs, and 55% said they did. Find the margin of error of this poll, at the 99% confidence level.

Give your answer to three decimals

If n=28, ¯xx¯(x-bar)=33, and s=7, find the margin of error at a 80% confidence level

Give your answer to two decimal places.

Solutions

Expert Solution

Solution :

Given that,

n =  160

Point estimate = sample proportion = =0.55

1 -   = 1-0.55 =0.45

At 99% confidence level the z is ,

  = 1 - 99% = 1 - 0.99 = 0.01

/ 2 = 0.01 / 2 = 0.005

Z/2 = Z0.005 = 2.576 ( Using z table )

  Margin of error = E = Z/2   * (((( * (1 - )) / n)

= 2.576* (((0.55*0.45) / 160 )

E = 0.1013

  Margin of error = E =0.10

(B)

Solution :

Given that,

s =7

n = 28Degrees of freedom = df = n - 1 =28 - 1 = 27

At 80% confidence level the t is ,

= 1 - 80% = 1 - 0.80 = 0.20

  / 2= 0.20 / 2 = 0.10

t /2,df = t0.10,27=1.314 ( using student t table)

Margin of error = E = t/2,df * (s /n)

= 1.314 * (7 / 28)

= 1.74

Margin of error = E =1.74


Related Solutions

In a recent poll, 120 people were asked if they liked dogs, and 60% said they...
In a recent poll, 120 people were asked if they liked dogs, and 60% said they did. Find the margin of error of this poll, at the 90% confidence level. Give your answer to three decimals
In a recent poll, 250 people were asked if they liked dogs, and 47% said they...
In a recent poll, 250 people were asked if they liked dogs, and 47% said they did. Find the margin of error of this poll, at the 90% confidence level. Give your answer to three decimals
1.) In a recent poll, 100 people were asked if they liked cats, and 81% said...
1.) In a recent poll, 100 people were asked if they liked cats, and 81% said they did. Based on this, construct a 99% confidence interval for the true population proportion of people who like cats. Use the following approximate critical values (z-scores) to perform the calculations by hand: --Use z = 1.645 for a 90% confidence interval --Use z = 2 for a 95% confidence interval --Use z = 2.576 for a 99% confidence interval. Give your answers as...
In a recent national poll, people were asked the following question: "In your opinion, how important...
In a recent national poll, people were asked the following question: "In your opinion, how important is it to improve the nation's inner-city schools?" The responses of city residents who do not have school-age children were compared to the national responses. A chi square test was used to analyze the data in order to determine whether there is a difference in responses between those who live in cities and do not have school-age children and the national responses. The results...
In a recent poll, 38% of people said that chocolate was their favorite flavor of ice...
In a recent poll, 38% of people said that chocolate was their favorite flavor of ice cream. Suppose that 20      adults are randomly selected.                                                                                                                                              Let X equal the number of people that answer chocolate is their favorite flavor of ice cream in the sample of 20. What is the probability distribution of X? (Be sure to list the specific distribution) (binomial, geometric, Poisson, exponential, uniform)    How many adults would you expect to say that chocolate is...
In a recent poll on world sadness, participants were asked to rate how sad they were...
In a recent poll on world sadness, participants were asked to rate how sad they were on a scale of 0 to 10, with 0 being completely unhappy and 10 being incredibly unhappy. The standard deviation of responses was 1.9 and the mean response was 6.3. What response would be the 90th percentile, rounded to one decimal place? What response would be in the third quartile, rounded to one decimal place? Please show your work! Any help is appreciated!
In Tokyo, 834 Japanese people were asked in a poll on whether they thought the Olympics...
In Tokyo, 834 Japanese people were asked in a poll on whether they thought the Olympics reduced international tension, increased international tension, or neither. 425 of them said that they thought the Olympics reduced international tension. Calculate a 97.5% confidence interval for the proportion of those who believed this.
A 2010 poll asked people in the United States whether they were satisfied with their financial...
A 2010 poll asked people in the United States whether they were satisfied with their financial situation. A total of 338 out of 833 people said they were satisfied. The same question was asked in 2012 , and 304 out of 1156 people said they were satisfied. Part 1 of 2 Your Answer is correct (a) Construct a 99.8% confidence interval for the difference between the proportions of adults who said they were satisfied in 2012 and 2010 . Let...
A 2010 poll asked people in the United States whether they were satisfied with their financial...
A 2010 poll asked people in the United States whether they were satisfied with their financial situation. A total of 338 out of 833 people said they were satisfied. The same question was asked in 2012 , and 304 out of 1156 people said they were satisfied. Part: 0 / 2 0 of 2 Parts Complete Part 1 of 2 (a) Construct a 99.8% confidence interval for the difference between the proportions of adults who said they were satisfied in...
A recent poll asked people whether they supported passing a constitutional amendment to ban burning of...
A recent poll asked people whether they supported passing a constitutional amendment to ban burning of the national flag using a 1 to 100 scale.”1” means that they do not support passing the amendment at all and “100” means they support it completely. The sample was random (from the population of US adults) and included 986 people, 400 of whom were women, and 586 were men. The mean score for women was 80.6, while the mean score for men was...
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT