Homework: Section 13.8 Homework Score: 0 of 1 pt X)13.8.59 Save 1 of 2 (1 comple

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Homework: Section 13.8 Homework Score: 0 of 1 pt X)13.8.59 Save 1 of 2 (1 complete) HW Score: 0%, 0 of 2 pts Question Help * Data were collected at a supermarket for the waiting time at the checkout during time periods where there were a constant number of checkout counters open. The total number of customers in the store and the waiting times (in minutes) were recorded. Based on a study of 30 time periods, the total number of customers in the store can be used to predict the waiting time at the checkout counter by the prediction line Y.--0.511 + 0.254x, For these data, Syx·0472. X #22.4, and SSX-32.382. Complete parts (a) through (c). Click here for page 1 of critical values oft Click here for page 2 of critical values oft a. Construct a 95% confidence interval estimate of the mean waiting time for all customers when there are 20 customers in the store. 4.12 minutes s Hy 20 (Round to two decimal places as needed.) s .01 minutes b. Construct a 95% prediction interval of the waiting time for an individual customer when there are 20 customers in the store. minutes SY20s minutes (Round to two decimal places as needed.)

Explanation / Answer

b)

95% predcition interval =3.50 <=Y <= 5.63

x             = 20 predcited value at X=20: 4.5690 std error prediction interval= s*(1+1/n+(x0-x)2/Sxx) = 0.5195 for 95 % CI value of t= 2.0484 margin of error E=t*std error                            = 1.0641 lower prediction bound=sample mean-margin of error = 3.50 Upper prediction bound=sample mean+margin of error= 5.63

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