=10.35.* Long a market leader in the production of heavy machinery, the Spellman Corporation recently has been enjoying a steady increase in the sales of its new lathe. The sales over the past 10 months are shown below.

Past Sales Month Year 1 Year 2 Year 3 Current Sales This Year January 352 317 338 364 February 329 331 346 343 March 365 344 383 391 April 358 386 404 437 May 412 423 431 458 June 446 472 459 494 July 420 415 433 468 August 471 492 518 555 September 355 340 309 387 October 312 301 335 364 November 567 629 594 662 December 533 505 527 581 Month Sales Month Sales 1 430 6 514 2 446 7 532 3 464 8 548 4 480 9 570 5 498 10 591 Because of this steady increase, management has decided to use causal forecasting, with the month as the independent variable and sales as the dependent variable, to forecast sales in the coming months.