Confidence Intervals - Proportions An interactive poll found that 347 of 2,394 adults aged 18 or older have at least one tattoo. (a) Obtain a point estimate for the proportion of adults who have at least one tattoo. (b) Construct a \( 95 \% \) confidence interval for the proportion of adults with at least one tattoo. (c) Construct a \( 99 \% \) confidence interval for the proportion of adults with at least one tattoo. (d) What is the effect of increasing the level of confidence on the width of the interval?

2.50. Uz jautājumu "Cik minūtes nepieciešamas, lai skolēns no mājām atnāktu uz skolu?" 60 pirmo klašu skolēnu vecāki atbildēja šādi: \( 5 ; 4 ; 28 ; 28 ; 11 ; 17 ; 17 ; 10 ; 19 ; 27 ; 22 ; 9 ; 26 ; 5 ; 19 ; 21 ; 21 ; 21 ; 7 ; 2 ; 8 ; 14 ; 5 ; 20 ; 13 ; 24 ; 14 ; 15 \); \( 3 ; 29 ; 13 ; 13 ; 22 ; 17 ; 2 ; 26 ; 30 ; 14 ; 8 ; 1 ; 20 ; 15 ; 16 ; 21 ; 20 ; 18 ; 25 ; 8 ; 12 ; 24 ; 9 ; 27 ; 8 ; 9 ; 13 ; 2 ; \) \( 8 ; 19 ; 16 ; 23 \). a) Sakārto datus tabulā, grupējot tos no 1 līdz \( 5 ; \) no 6 līdz 10; no 11 līdz 15; no 16 līdz 20; 21 un vairāk minūtes! b) Nosaki datu modu! c) Aprēkini katras datu grupas relatīvo biežumu! d) Izmantojot tabulas datus, uzzīmē relatīvo biežumu stabinu diagrammu!

21. Una empresa de investigación de mercado emplea una muestra de individuos para calificar el potencial de compra de un determinado producto antes y después de que los individuos vean un comercial de televisión acerca del mismo. La calificación del potencial de compra se hace con una escala del 0 al 10 , con los valores más altos indicando un mayor potencial de compra. En la hipótesis nula se establece que la media de las calificaciones de "después" será menor o igual a la media de las calificaciones "antes". El rechazo de esta hipótesis indica que el comercial me- jöra la media de la calificación al potencial de compra. Use \( \alpha=0.05 \) y los datos de la tabla si- guiente para probar esta hipótesis y haga un comentario sobre la utilidad del comercial. Calificación al potencial de compra Individuos Después 1

Why is data collection appropriate for this two-sample proportion procedure? Because the order of applying the two treatments to each doctor was randomized in this matched pairs design. Because two separate simple random samples were taken-one from each population. Because the doctors were randomly allocated to the two treatments (aspirin and placebo).

Baseball regression line prediction: Suppose the regression line for the number of runs scored in a season, \( y \), is given by \( \hat{y}=-730+4300 x \), where \( x \) is the team's batting average. a. For a tearn with a batting average of 0.235 , find the expected number of runs scored in a season. Round your answer to the nearest whole number. b. If we can expect the number of runs scored in a scason is 480 , then what is the assumed team's batting average? Round your onswer to three deeima! places.

You run a regression analysis on a bivariate set of data ( \( n=88 \) ), You obtain the regression equation \[ y=0.231 x-8.928 \] with a correlation confficient of \( r=0.38 \) (which is significant at \( \alpha=0.01 \) ), You want to predict what value (on average) for the explanatory variable will give you a value of 90 on the response variable. What is the predicted explanatory value? \( x=\square \)