Three experiments investigating the relation between need for cognitive closure and persuasion were performed. Part of the study involved administering a "need for closure scale" to a group of students enrolled in an introductory psychology course. The "need for closure scale" has scores ranging from 101 to 201. For the79students in the highest quartile of the distribution, the mean score wasx=176.70. Assume a population standard deviation of=7.69. These students were all classified as high on their need for closure. Assume that the79 students represent a random sample of all students who are classified as high on their need for closure. Find a 95% confidence interval for the population mean scoreon the "need for closure scale" for all students with a high need for closure. (Round your answers to two decimal places.)

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A research group conducted an extensive survey of3147wage and salaried workers on issues ranging from relationships with their bosses to household chores. The data were gathered through hour-long telephone interviews with a nationally representative sample. In response to the question, "What does success mean to you?"1646responded, "Personal satisfaction from doing a good job." Letpbe the population proportion of all wage and salaried workers who would respond the same way to the stated question. Find a 90% confidence interval forp. (Round your answers to three decimal places.)

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The personnel office at a large electronics firm regularly schedules job interviews and maintains records of the interviews. From the past records, they have found that the length of a first interview is normally distributed, with mean=38minutes and standard deviation=8minutes. (Round your answers to four decimal places.)

(a) What is the probability that a first interview will last 40 minutes or longer?

(b)Seventeenfirst interviews are usually scheduled per day. What is the probability that the average length of time for theseventeeninterviews will be 40 minutes or longer?

How hot is the air in the top (crown) of a hot air balloon? Information fromBallooning: The Complete Guide to Riding the Winds, by Wirth and Young (Random House), claims that the air in the crown should be an average of 100C for a balloon to be in a state of equilibrium. However, the temperature does not need to be exactly 100C. What is a reasonable and safe range of temperatures? This range may vary with the size and (decorative) shape of the balloon. All balloons have a temperature gauge in the crown. Suppose that50readings (for a balloon in equilibrium) gave a mean temperature ofx= 97C. For this balloon,16C.

(a) Compute a 95% confidence interval for the average temperature at which this balloon will be in a steady-state equilibrium. (Round your answers to one decimal place.)

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C

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C