题干

电视台与某广告公司签约播放两部影片集,其中影片集甲每集播放时间为19分钟(不含广告时间,下同),广告时间为1分钟,收视观众为60万;影片集乙每集播放时间为7分钟,广告时间为1分钟,收视观众为20万,广告公司规定每周至少有7分钟广告,而电视台每周只能为该公司提供不多于80分钟的节目时间(含广告时间).

(Ⅰ)问电视台每周应播放两部影片集各多少集,才能使收视观众最多;

(Ⅱ)在获得最多收视观众的情况下,影片集甲、乙每集可分别给广告公司带来a和b(万元)的效益,若广告公司本周共获得3万元的效益,记S=

16
a
+ 10
b
为效益调和指数(单位:万元),求效益调和指数的最小值.
上一题 下一题 0.0难度 选择题 更新时间:2019-10-16 01:13:14

答案(点此获取答案解析)

解:(Ⅰ)设片集甲乙分别播放x,y集,

由题意得到, {x+y720x+

同类题5

根据短文内容,从下列A-F选项中选出能概括每一段主题的最佳选项。 选项中有一项为多余项。

A. Wash yourself as often as possible

B. Avoid being in hot sun

C. Keep away from smoke and alcohol

D. The importance of skin

E. Have a balanced diet

F. Be sure to have enough water

    ____When it comes to your skin, there is an important fact that you must keep in mind: Your skin is the largest organ of your body. Therefore, skin health and protection is crucial. Your skin does everything for you. It can keep your body hydrated and regulate your body's temperature.

    Now, here are some helpful tips for you to protect your skin:

    ____Protection against harmful rays from the sun is one of the most important steps that you need to take. With this in mind it is necessary for you to avoid strong sunlight as often as possible. As for sunscreen you need to buy products that contain UVA-1, UVA-2 and UVB protection.

    ____Your diet also has a direct impact on the health of your skin. The most important aspect of your diet in relation to the health of your skin is to make certain that you eat a proper amount of food items that contain the proteins and nutrients necessary for cellular maintenance, repair and regeneration.

    ____Water is also important to the health of your skin. While you certainly have heard it before, it actually is true that you should drink at least eight 8-ounce glasses of fresh water every day. There are many health benefits to be derived from drinking water daily, including maintaining healthy skin.

    ____Finally, when it comes to the health of your skin today and into the future you should avoid smoking all together. In addition, you should drink alcohol only in moderation. Both smoking and excessive alcohol consumption can negatively impact the health of your skin in significant ways.