1. The demand for pizzas from Sam\'s Pizza and Tuna Salad Shoppe is assumed to p
ID: 3358128 • Letter: 1
Question
1. The demand for pizzas from Sam's Pizza and Tuna Salad Shoppe is assumed to possess a normal distribution. The number of pizzas ordered from Sam's during each of the past eight weeks was 172, 136, 193, 141, 138, 147, 129, and 169. Some useful statistics from this sample: X = 153.125 s2 = 498.125 s = 22.3187 (35 pt) Determine a 90% confidence interval for the mean weekly demand. a. b. (35 pt) Determine a 90% confidence upper bound for the standard deviation of the weekly demand c. (35 pt) with 90% confidence, determine an interval estimate that predicts next week's demand.Explanation / Answer
a)std error of mean =std deviation/(n)1/2 =22.3187/(8)1/2 =7.8909
for 90% CI and (n-1=8) degree of freedom; crtiical value of t =1.8946
therfore 90% confidence interval for mean weekly demand =sample mean -/+ t*std error =138.1752 to 168.0748
b) for 90% confidence of upper bound; critical value of t=1.4149
90% confidence upper bound for mean weekly demand =sample mean + t*std error =164.2900
c)
for 90% prediction interval ; std error for predicted value =std deviation(1+1/n)1/2 =23.6726
for 90% CI and (n-1=8) degree of freedom; crtiical value of t =1.8946
therefore 90% prediction interval for next week's demand =sample mean -/+ t*std error =108.2755 to 197.9745
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