1) Professor Jennings claims that only 35% of the students at Flora college work while attending school. The dean thinks that the professor has underestimated the number of students with part time or full time jobs. A random sample of 81 students shows that 39 have jobs. Do the data indicate that more than 35% of the students have jobs? (use a 5% level of significance)

2) The highway department is testing two types of reflecting paint for concrete bridge end pillars. The two kinds of paint are alike in every respect except that one is orange and the other is yellow. The orange paint is applied to 12 bridges and the yellow to 12 bridges. After 1 year, reflectometer readings were made on all bridge end pillars. (higher reading = higher visibility) For the orange paint, the mean reflectometer reading was X bar1 = 9.4, with standard deviation s1=2.1. For the yellow, the mean was X bar 2 = 6.9, with standard deviation s2 = 2.0. Based on these data, can we conclude that the yellow paint has less visibility after 1 year? (use 1% level of significance)

3) A study is made of residents in pheonix and its suburbs concerning the proportion of residents who subscribe to sporting news. A random sample of 88 urban residents showed that 12 subscribed, and a random sample of 97 suburban residents showed that 18 subscribed. Does this indicate that a higher proportion of suburban residents subscribe to sporting news? Use 5% level of significance.

5) Six sets of identical twins were randomly selected from a population of identical twins. One child was taken at random from each pair to form an experimental group. These children participated in a program designed to promote creative thinking. The other child from each pair was part of the control group that did not participate in the program to promote creative thinking. At the end of the program, a creative problem solving test was given, with the results shown in the following table:

Twin pair | A B C D E F
Experimental group | 53 35 12 25 33 47
Control group | 39 21 5 18 21 42

Higher schores indicate better performance in creative problem solving. Do the data support the claim that the program of the experimental group did promote creative thinking? (use 1% level of significance)

6) The manufacturer of a sports car claims that the fuel injection system lasts 48 months before it needs to be replaced. A consumer group tests this claim by surveying a random sample of 10 owners who had the fuel injection system replaced. The ages of the cars at the time of replacement were (in months): 29, 42, 49, 48, 53, 46, 30, 51, 42, 52.