题干

某种产品的广告费用支出 x  与销售额 y 之间有如下的对应数据:
x
2
4
5
6
8
y
30
40
60
50
70
( 参考公式:用最小二乘法求线性回归方程系数公式 b^=
∑
i
=
1
n
x
i
y
i
−
n
x
¯
y
¯
∑
i
=
1
n
x
i
2
−
n
x
¯
2
,a^=y¯−b^x¯
)
上一题 下一题 0.0难度 选择题 更新时间:2019-04-11 01:36:00

答案(点此获取答案解析)

同类题1

阅读理解

The World's Coolest Places

    There's nothing wrong with a relaxing week at the beach. But travel can also be an education, a step toward empathy(共鸣) and international understanding, so for those longing to escape the crowds this summer, encounter new worlds and return with a tale, here're a few little-known travel destinations I recommend.

⒈Bikini Atoll, Marshall Islands.

    This coral island in the Pacific Ocean, site of nuclear weapons tests decades ago, is now brilliantly beautiful and the deserted white-sand beaches are lined with coconut palms and scattered with seashells. The island is a reminder of the redemptive(救赎的) power of time and nature.

⒉Potosi, Bolivia.

    No city in Latin America is more beautiful than Potosi, Bolivia, where Europeans discovered a huge silver mountain centuries ago. Tourists can descend(下降) the silver mines to experience extremely hot and dusty tunnels, talk to the miners, get a glimpse of life image for Bolivians there and have new empathy for the miners.

⒊Victoria Falls, Zimbabwe.

    Maybe our family start at Victoria Falls, which wets you with spray, making Niagara Falls a backyard stream. Then we rent a car and make our way to Hwange National Park, empty of people but crowded with various animals. Zimbabwe has fewer tourists than South Africa, and there's less crime as well.

⒋Amritsar, India.

    The Golden Temple, Sikhism's holiest shrine(神殿), is a delightful place to contemplate the draw of faith. A four-century-old temple set in a lake attracts Sikhs(锡克教徒) worldwide. Walking the circuit of the lake, with your head covered, and putting up in temple buildings can be a full experience.

同类题3

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

How to become a better reader

    Language and literacy (读写能力) are among humans' greatest inventions. Evolving(演变)over the course of human history, languages are a reflection of our cultural and societal attitudes. Today, surrounded(包围)by social media, television, movies, and, of course, books, the ability to read and write is important to expressing one's feelings. Most humans acquire language in early childhood and speak fluently when they are about three years old, but our continued relationship with language gives shape and meaning to our lives.____

    Take it slow. Many readers feel that they read too slowly, especially compared with others.____The best readers are flexible(灵活的)— slowing down when needed — and always have a dictionary at hand.

    Read aloud. When humans first began reading written words, it was unusual to read in silence.____Try listening to the author reading their own work — you'll be surprised to find how clearly it comes through on the page.

    Write. Writing and reading go hand-in-hand: how and what you read affects how and what you write, and the best readers often make the best writers. But while much can be learned from close, repeated readings, there are many pleasures to language that can only be experienced through the practice of writing.____

    Tell your friends. All of the literature is essentially communication from an individual's inner voice to an audience.____It's a good way to see the world from someone else's eyes and, in the process, carefully examine your own reaction to what you're reading.

A. But the truth is that the faster you read, the less likely you are to understand fully what you're reading.

B. Can you remember the first piece of writing that transported you to another world?

C. There is something magical about sharing books with friends or a book club.

D. Try writing every day for a month, and you will never read the same again.

E. Reading out loud is one of the best ways to improve your reading ability.

F. Here are 4 ways to become a better reader.

G. In no time, you'll be appreciating novels like fine wine.