Preterit

Construct an interval estimate for the given parameter using the given sample statistic and margin of error. For μ1-μ2, using x¯1-x¯2=0 with margin of error 10 .

(-10,10)

Construct an interval estimate for the given parameter using the given sample statistic and margin of error. For p, using p̂=0.38 with margin of error 0.05 .

(0.33,0.38)

Construct an interval estimate for the given parameter using the given sample statistic and margin of error. For μ, using x̅=26 with margin of error 3 .

(23,29)

A study of n=2252 adults age 18 or older found that 72% of the cell phone users send and receive text messages.1 A study of n=800 teens age 12 to 17 found that 87% of the teen cell phone users send and receive text messages. What is the best estimate for the difference in the proportion of cell phone users who use text messages, between adults (defined as 18 and over) and teens? Let group 1 be the adult cell phone users and let group 2 be the teen cell phone users. (a) Give the notation (as a difference with a minus sign) for the quantity we are trying to estimate. (b)Give the notation for the quantity that gives the best estimate. (c) Give the value of the best estimate.

(a) p1-p2 (b) p̂1-p̂2 (c) -0.15

A 95% confidence interval for a mean is 106.7 to 112.9 . Is the value given a plausible value of μ? (plausible or not plausible) (a) μ=108.3 (b) μ=107.7 (c) μ=103.6

(a) plausible (b) plausible (c) not plausible

In preparing for a test on a set of material, is it better to study one topic at a time or to study topics mixed together? In one study,1 a sample of fourth graders were taught four equations. Half of the children learned by studying repeated examples of one equation at a time, while the other half studied mixed problem sets that included examples of all four types of calculations grouped together. A day later, all the students were given a test on the material. The students in the mixed practice group had an average grade of 77, while the students in the one-at-a-time group had an average grade of 38. What is the best estimate for the difference in the average grade between fourth-grade students who study mixed problems and those who study each equation independently? Let group 1 be the fourth-grade students who study mixed problems and let group 2 be the fourth-grade students who study each equation independently. (a) Give the notation (as a difference with a minus sign) for the quantity we are trying to estimate. (b) Give the notation for the quantity that gives the best estimate. (c) Give the value of the best estimate.

(a) μ1 - μ2 (b) x̅1 - x̅2 (c) 39