The accompanying table represents a frequency distribution of the duration times (in seconds) of 40 eruptions of the Old Faithful geyser, as listed in Data Set 15 in Appendix B.

a. What is the class width?

b. What are the upper and lower class limits of the first class?

c. What are the upper and lower class boundaries of the first class?

d. Does the distribution of duration times appear to be a normal distribution?

Data Set 15

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Interval Interval Prediction Duration Before After Height (ft) Error (sec) (min) (min) (min) 98 92 95 92 240 140 237 92 140 148 -2 250 95 243 87 96 100 130 -7 125 110 255 90 120 90 65 -4 260 65 92 136 178 92 72 125 259 95 93 115 245 93 98 120 -1 234 98 94 120 213 94 80 93 120 255 93 150 235 93 83 89 140 -1 250 96 136 110 245 66 89 89 120 -5 93 148 -1 269 89 86 130 251 86 69 97 130 -8 234 105 136 105 252 92 130 254 92 89 115 273 89 93 136 130 -3 266 93 112 284 112 88 138 20 252 95 105 94 120 269 105 120 13 250 94 90 98 120 95 261 90 -2 253 98 81 140 255 81 69 101 125 -11 280 94 130 270 94 92 130 92 106 241 106 110 272 93 96 110 125 14 294 93 150 220 108 87 21 253 87 97 130 -5 245 97 86 120 274 102 92 95 10