The attached data set contains historical sales data for a retailer. Fit a 3 period moving average model. What is the forecast for period 21? Enter you answer as a whole number.

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Home Insert Draw Page Layout Formulas Data Review View Te X Cut Copy Calibri (Body) 12 A AI = = Paste BIU V V A V === Format K22 fox B D F F G H 1 Obs # 2 3 4 5 6 7 8 9 10 9 Sep 11 12 13 14 15 16 17 18 19 20 21 22 Month Passengers Year Month# Mname 1 Jan-49 112 1949 1 Jan 2 Feb-49 118 1949 2 Feb 3 Mar-49 132 1949 3 Mar 4 Apr-49 129 1949 4 Apr 5 May-49 121 1949 5 May 6 Jun-49 135 1949 6 Jun 7 Jul-49 148 1949 7 Jul 8 Aug-49 148 1949 8 Aug 9 Sep-49 136 1949 10 Oct-49 119 1949 10 Oct 11 Nov-49 104 1949 11 Nov 12 Dec-49 118 1949 12 Dec 13 Jan-50 115 1950 1 Jan 14 Feb-50 126 1950 2 Feb 15 Mar-50 141 1950 3 Mar 16 Apr-50 135 1950 4 Apr 17 May-50 125 1950 5 May 18 Jun-50 149 1950 6 Jun 19 Jul-50 170 1950 7 Jul 20 Aug-50 170 1950 8 Aug 21 Sep-50 158 1950 9 Sep 22 Oct-50 133 1950 10 Oct 23 Nov-50 114 1950 11 Nov 24 Dec-50 140 1950 12 Dec 25 Jan-51 145 1951 1 Jan 26 Feb-51 150 1951 2 Feb 27 Mar-51 178 1951 3 Mar 28 Apr-51 163 1951 4 Apr 29 May-51 172 1951 30 Jun-51 178 1951 6 Jun 31 Jul-51 199 1951 7 Jul 32 Aug-51 199 1951 8 Aug 33 Sep-51 1951 9 Sep 34 Oct-51 162 1951 10 Oct 35 Nov-51 146 1951 11 Nov 36 Dec-51 166 1951 12 Dec 37 Jan-52 171 1952 1 Jan 38 Feb-52 180 1952 2 Feb 39 Mar-52 193 1952 3 Mar 40 Apr-52 181 1952 4 Apr 41 May-52 183 1952 5 May 23 24 25 26 27 28 29 30 5 May 31 32 184 33 34 35 36 37 38 39 40 41 42 Data + Ready AutoSave OFF 9 O... Home Insert Draw Page Layout Formulas Data Review View Calibri (Body) X Cut Copy v 12 y AP X = = 80 Paste BIU V o v Av + Format K22 x fx A B D E F G 1952 42 43 41 42 43 44 45 183 218 230 242 209 191 1952 1952 1952 44 46 45 47 172 194 48 49 50 51 46 47 48 49 50 51 196 196 236 1952 1952 1952 1952 1953 1953 1953 1953 1953 52 53 52 235 54 55 56 57 53 54 55 56 57 229 243 264 272 237 58 211 180 59 60 61 62 58 59 60 61 62 May-52 Jun-52 Jul-52 Aug-52 Sep-52 Oct-52 Nov-52 Dec-52 Jan-53 Feb-53 Mar-53 Apr-53 May-53 Jun-53 Jul-53 Aug-53 Sep-53 Oct-53 Nov-53 Dec-53 Jan-54 Feb-54 Mar-54 Apr-54 May-54 Jun-54 Jul-54 Aug-54 Sep-54 Oct-54 Nov-54 Dec-54 Jan-55 Feb-55 Mar-55 Apr-55 May-55 Jun-55 Jul-55 Aug-55 Sep-55 Oct-55 5 May 6 Jun 7 Jul 8 Aug 9 Sep 10 Oct 11 Nov 12 Dec 1 Jan 2 Feb 3 Mar 4 Apr 5 May 6 Jun 7 Jul 8 Aug 9 Sep 10 Oct 11 Nov 12 Dec 1 Jan 2 Feb 3 Mar 4 Apr 5 May 6 Jun 7 Jul 8 Aug 9 Sep 10 Oct 11 Nov 12 Dec 1 Jan 2 Feb 3 Mar 63 64 201 204 188 235 227 234 264 63 64 65 65 66 67 66 67 68 1953 1953 1953 1953 1953 1953 1953 1954 1954 1954 1954 1954 1954 1954 1954 1954 1954 1954 1954 1955 1955 1955 1955 1955 1955 1955 1955 69 302 293 259 229 68 70 69 70 71 72 203 71 72 229 73 74 75 242 73 74 76 4 Apr 77 78 nu 79 80 78 79 80 233 267 269 270 315 364 347 312 274 5 May 6 Jun 7 Jul 81 8 Aug 82 81 82 1955 1955 9 Sep 10 Oct 83 Data + Ready AutoSave OFF 9 O... Home Insert Draw Page Layout Formulas Data Review View X Cut Copy Calibri (Body) v 12 y = = Paste BIU V V AY 1 Format K22 x fx A B D E F G 83 82 83 84 274 237 278 284 1955 1955 1955 84 85 86 85 86 87 277 1956 1956 1956 88 317 87 88 89 89 90 91 92 93 313 318 374 413 405 1956 1956 1956 90 91 92 93 1956 1956 1956 1956 94 95 355 306 271 306 94 95 96 96 97 98 97 98 315 301 99 100 101 99 100 102 103 104 Oct-55 Nov-55 Dec-55 Jan-56 Feb-56 Mar-56 Apr-56 May-56 Jun-56 Jul-56 Aug-56 Sep-56 Oct-56 Nov-56 Dec-56 Jan-57 Feb-57 Mar-57 Apr-57 May-57 Jun-57 Jul-57 Aug-57 Sep-57 Oct-57 Nov-57 Dec-57 Jan-58 Feb-58 Mar-58 Apr-58 May-58 Jun-58 Jul-58 Aug-58 Sep-58 Oct-58 Nov-58 Dec-58 Jan-59 Feb-59 Mar-59 1956 1956 1957 1957 1957 1957 1957 1957 1957 1957 1957 1957 101 102 356 348 355 422 465 10 Oct 11 Nov 12 Dec 1 Jan 2 Feb 3 Mar 4 Apr 5 May 6 Jun 7 Jul 8 Aug 9 Sep 10 Oct 11 Nov 12 Dec 1 Jan 2 Feb 3 Mar 4 Apr 5 May 6 Jun 7 Jul 8 Aug 9 Sep 10 Oct 11 Nov 12 Dec 1 Jan 2 Feb 3 Mar 4 Apr 5 May 6 Jun 7 Jul 8 Aug 9 Sep 10 Oct 11 Nov 12 Dec 1 Jan 2 Feb 3 Mar 103 104 467 105 106 107 108 109 110 105 106 107 404 347 305 336 340 108 109 1957 1957 1958 111 110 111 318 362 112 113 112 348 363 113 114 114 115 116 117 118 119 1958 1958 1958 1958 1958 1958 1958 115 116 117 435 491 505 404 359 310 1958 1958 1958 1958 118 119 120 121 120 121 337 122 123 124 360 342 122 1959 1959 1959 123 406 Data + Ready AutoSave OFF 9 O... Home Insert Draw Page Layout Formulas Data Review View Tell me Calibri (Body) V 12 ~ A Ai = = ab w X Cut Copy v Format lil III Paste BIU V ~A~ E + M K22 fx A B D E F G G H 124 125 126 123 124 125 406 396 420 472 127 126 127 128 129 128 548 559 463 129 130 131 130 131 132 133 407 362 405 417 Mar-59 Apr-59 May-59 Jun-59 Jul-59 Aug-59 Sep-59 Oct-59 Nov-59 Dec-59 Jan-60 Feb-60 Mar-60 Apr-60 May-60 Jun-60 Jul-60 Aug-60 Sep-60 Oct-60 Nov-60 - Dec-60 1959 1959 1959 1959 1959 1959 1959 1959 1959 1959 1960 1960 1960 1960 1960 1960 132 133 134 135 136 137 3 Mar 4 Apr 5 May 6 Jun 7 Jul 8 Aug 9 Sep 10 Oct 11 Nov 12 Dec 1 Jan 2 Feb 3 Mar 4 Apr 5 May 6 Jun 7 Jul 8 Aug 9 Sep 10 Oct 11 Nov 12 Dec 134 391 419 135 136 138 137 461 472 535 138 139 140 141 142 622 606 508 139 140 141 142 143 144 145 146 147 148 149 150 151 1960 1960 1960 1960 1960 1960 143 144 461 390 432 Discover more about your data 152 153 154 155 156 157 158 159 160 161 162 163 164 165 Data + Ready