Question

Refer to the accompanying data set of mean drive-through service times at dinner in seconds at two fast food restaurants. Construct a 99% confidence interval estimate of the mean drive-through service time for restaurant X at dinner then do the same for restaurant Y

Restaurant X Restaurant Y
83 101
119 131
116 155
143 111
263 174
178 135
122 111
154 123
166 128
215 128
328 131
303 136
179 230
109 217
154 296
149 126
94 95
234 139
244 238
183 138
149 145
203 203
171 154
116 143
65 139
206 149
178 154
112 138
140 171
176 133
193 237
195 240
232 247
191 231
356 230
305 173
212 89
192 109
183 51
190 172
111 75
152 144
176 144
157 97
172 123
155 144
161 129
127 182
138 153
309 123

Answer 1

For Restaurant X, and

Similarly for Restaurant Y, and

Now for X and Y, as n=50, we wll use z distribution to find CI

z value for 95% CI is 1.96 as

So For X, Margin of Error is

So Confidence Interval is

Similarly for Y, Margin of Error is

So Confidence Interval is