Extremely smoky dwellings are common in the world's underdeveloped countries, where open fire pits in the home traditionally provide heat for cooking and warmth.This is thought to increase the risk of developing lung cancer.For decades, many counties have encouraged their citizens to install stoves with chimneys that funnel smoke away from living spaces.It was thought that these vented stoves generated substantially less soot and other airborne particulate matter than the traditional open fire pits did.To determine whether the switch to vented stoves decreased lung cancer rates, a study was conducted in one such country.Data were gathered in 1990 in one region of this country by randomly selecting 1000 homes from that region that had switched to the vented stoves and 1100 homes from that region that had not switched.Data were gathered on both men and women in the study.Between 1980 and 1996, 72 nonsmoking men whose homes used vented stoves and 102 nonsmoking men whose homes had not been converted to those stoves developed lung cancer.

(a)Was the program effective in decreasing lung cancer rates among men?Support your answer with appropriate statistical evidence.

(b)Can we conclude that using vented stoves rather than open fire pits causes thereduction ofthe incidence of lung cancer in all converted homes in this country?Justify your answer.