问题 问答题

本电视机生产厂家去年销往农村的某品牌电视机每台的售价y(元)与月份x之间满足函数关系y=-50x+2600,去年的月销售量p(万台)与月份x之间成一次函数关系,其中每个月的销售情况如下表:

月份1月5月
销售量3.9万台4.3万台

(1)求该品牌电视机在去年哪个月销往农村的销量金额最大最大是多少

(2)由于受国际金融危机的影响,今年1、2月份该品牌电视机销往农村的售价都比去年12月份下降了m%,且每月的销售量都比去年12月份下降了1.5m%.国家实施“家电下乡”政策,即对农村家庭购买新的家电产品,国家按该产品售价的13%给予了财政补贴.受此政策的影响,今年3至5月份,该厂家销售到农村的这种电视机在保持今年2月份的售价不变的情况下,平均每月的销售量比今年2月份增加了1.5万台.若今年3至5月份国家对这种电视机的销售共给予了财政补贴936万元,求m的值(保留一位小数).

答案

参考答案:

(1)设p与x的函数关系为P=kx+b(k≠0),根据题意,得:

设月销售金额为ω万元,则

ω=py=(0.1x+31.8)(-50x+2600),

化简,得ω=-5x2+70x+9880,

所以,ω=-5(x-7)2+10125.

当x=7时,叫取得最大值,最大值为10125.

答:该品牌电视机在去年7月份销往农村的销售金额最大,最大是10125万元.

(2)去年12月份每台的售价为-50×12+2600=2000(元),

去年12月份的销售量为0.1×12+3.8=5(万台),

根据题意,得2000(1-m%)×[5(1-1.5m%)+1.5]×13%×3=936。

令m%=t,原方程可化为7.5t2-14t+5.3=0.

∴t1≈0.528,t2≈1.339(舍去).

答:m的值约为52.8.

单项选择题

The United States experienced some of the most extreme weather events in its history this spring, including deadly outbreaks of tornadoes, near-record flooding, drought and wildfires. Damages from these disasters have already passed $ 32 billion, and the hurricane season, which is just beginning, is projected to be above average, according to the National Oceanic and Atmospheric Administration.

Government scientists said Wednesday that the frequency of extreme weather has increased over the past two decades, in part as a result of global warming caused by the accumulation of carbon dioxide in the atmosphere. But they were careful not to blame humans for this year’s rash of deadly events, saying that in some ways weather patterns were returning to those seen at the beginning of the last century. "Looking at long-term patterns since 1980, indeed, extreme climatological and meteorological events have increased," said Thomas R. Karl, director of NOAA’s National Climatic Data Center. "But in the early part of the 20th century, there was also a tendency for more extreme events followed by a quiet couple of decades. "

Presenting a new NOAA report on 2011 extreme weather, Dr. Karl said that extremes of precipitation have increased as the planet warms and more water evaporates from the oceans. He also said models suggest that as carbon dioxide builds up in the atmosphere and heats the planet, droughts will increase in frequency and intensity. "But it is difficult and unlikely to discern a human fingerprint, if there is one, on the drought record of the United States," he said.

Some other climate scientists were more categorical about the human contribution to extreme climate events. Kevin Trenberth, distinguished senior scientist at the National Center for Atmospheric Research, said that when the greenhouse effect caused by burning fossil fuels is added to the natural variability of climate, weather disasters can be expected to occur more frequently. "Global warming is contributing to an increased incidence of extreme weather because the environment in which all storms form has changed from human activities," Dr. Trenberth said in a telephone interview Wednesday. "Records are not just broken, they are smashed. It is as clear a warning as we are going to get about prospects for the future. "

April was a particularly devastating month for tornadoes and rainfall, with 875 tornadoes reported during the month and heavy rain and snowmelt contributing to Mississippi River flooding later in the spring that surpassed the historic floods of 1927 and 1937. So far this year, there have been nearly 1,400 preliminary tornado reports nationwide; those reports will most likely be whittled down to about 900 confirmed tornadoes, the second-highest annual total recorded in modern times. The record is 1,011 confirmed tornadoes in 2008. The year also is on track to be one of the deadliest, with 536 fatalities so far from tornadoes, placing 2011 in sixth place in United States history and the deadliest since 1936.

According to Dr. Karl, extreme weather is mainly attributable to()

A. arbitrary human activities

B. changing weather patterns

C. an increase in climatological events

D. human failure to control the weather

单项选择题 A2型题