Question

Which inference method?

a. Drowning in bathtubs is a major cause of death in children less than$5$years old. A random sample of parents was asked many questions related to bathtub safety. Overall,$85\%$of the sample said they used baby bathtubs for infants. Estimate the percent of all parents of young children who use baby bathtubs.

b. How seriously do people view speeding in comparison with other annoying behaviors? A large random sample of adults was asked to rate a number of behaviors on a scale of$1$(no problem at all) to$5$(very severe problem). Do speeding drivers get a higher average rating than noisy neighbors?

c. You have data from interviews with a random sample of students who failed to graduate from a particular college in$7$years and also from a random sample of students who entered at the same time and did graduate within$7$years. You will use these data to estimate the difference in the percent's of students from rural backgrounds among dropouts and graduates.

d. Do experienced computer-game players earn higher scores when they play with someone present to cheer them on or when they play alone? Fifty teenagers with experience playing a particular computer game have volunteered for a study. We randomly assign$25$ of them to play the game alone and the other$25$to play the game with a supporter present. Each player’s score is recorded.

Short answer

(a) The inference method is a one-sample z interval for proportion.

(b) The inference method is a one-sample t-interval for the mean.

(c) The inference method is a one-sample z interval for proportion.

(d) The inference method is a one-sample z interval for proportion.

Step-by-step solution

Part (a) Step 1: Given Information

We are given that drowning in bath tubs is major cause of death of children and we have to find out the inference method.

Part (a) Step 2: Explanation

According to the question, when we use null hypothesis or confidence interval for proportion, we use z-test or z-interval and it is given in the sample that the proportion of infants death in drawing bathtubs and for that use z-interval.

Hence, z-interval is used.

Part (b) Step 1: Given Information

We are given that people view speeding in comparison with other annoying behaviors, and we have to find out the inference method.

Part (b) Step 2: Explanation

According to the question, when we use null hypothesis or confidence interval for mean, we use t-test or t-interval, and it is given in the sample that the two subjects are taken and they are the same and dependent on each other, and use paired test or paired interval.

Hence, t-interval is used.

Part (c) Step 1: Given Information

We are given data from interviews with a random sample of students who failed to graduate from a particular college and we have to find out the inference method.

Part (c) Step 2: Explanation

According to the question, when we use null hypothesis or confidence interval for proportions, we use z-test or z-interval, and it is given in the sample that the two subjects are taken and they are different and independent of each other, and use sample test or sample interval.

Hence, z-interval is used.

Part (d) Step 1: Given Information

We are given computer game-player experience to earn higher scores when they play with someone present to cheer them on or when they play alone, and we have to find out the inference method.

Part (d) Step 2: Explanation

According to the question, when we use null hypothesis or confidence interval for proportions, we use z-test or z-interval, and it is given in the sample that the two subjects are taken and they are different and independent of each other, and use sample test or sample interval.

Hence, z-interval is used.