题干

甲、乙两组数据分别为甲:28,31,39,45,42,55,58,57,66;乙:29,34,35,48,42,46,55,53,55,67则甲、乙的中位数分别是(    )   

A:45,44

B:45,47

C:42,46

D:42,47

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答案(点此获取答案解析)

B

同类题3

    Sometimes people are not clear about what kind of food is healthy, and what kind of food may do harm to our health. The USDA has prepared a food guide to help people learn about which kind of food is the healthiest to eat. The food guide describes six main food groups: meat (like fish and chicken), dairy (like milk and cheese),grains (like bread and rice), fruit and vegetables. The last group is fats and sweets. The USDA also suggests how much of each food group is healthy to eat daily. Though this guide was prepared by the US government, it is very useful for people all over the world.
    As a result of years of study, we know that too much animal fat is bad for our health. For example, Americans eat a lot of meat and only a small amount of grains, fruit and vegetables. Because of the way they eat, they have a high rate of cancer and heart disease. In Japan, people eat large amounts of grains and very little meat. The Japanese also have a very low rate of cancer and heart disease. The Japanese live longer than anyone else in the world. However, when Japanese people move to the US, the rate of heart disease and cancer goes up as their eating habit changes. And as hamburgers, ice creams and other high-fat foods become popular in Japan, the rate of heart disease and cancer is going up there as well. People are also eating more meat and dairy food in other countries, in which the disease rate is going up along with the change of the way people eat. Doctors everywhere suggest people eat more grains, fruit and vegetables and less meat and dairy food.
    Eating healthily is important for children as well as their parents. When parents have poor eating habits, their children usually do, too. After all, children eat in the same way as their parents. When parents eat healthy food, the children will learn to enjoy it, too. Then they will develop good eating habits. Doctors suggest parents give their children healthier food such as fruit, vegetables and juice.
    Everyone wants to live a long, healthy life. We know that the food we eat affects us in different ways. For example, doctors believe that fruit and vegetables can really protect people from many different diseases. On the other hand, animal fat can cause diseases. We can change our eating habits now and enjoy many years of healthy living.

同类题4

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。

    Here, sleep experts clear up some of the biggest misunderstandings about sleep they see with their patients, which could weaken your ability to have a night of good sleep.

Myth: ____

    The latest research shows that the right amount of sleep may vary from person to person and should leave you feeling energized the next day. I'm a sleep doctor. Take myself for example. ____.

Myth: Don't fall asleep with the TV on.

    I've cured more people suffering from sleep problems than you can imagine by telling  people it's OK to fall asleep with the TV on. ____Control the watching time so it doesn't affect your sleep later in the night.

Myth: You can catch up on lost sleep on the weekend.

    ____ A Harvard study found that even if you sleep for an extra 10 hours on the weekend to make up for only sleeping six hours a night for two weeks, those extra hours won't improve  your reaction times or ability to focus. Plus, sleeping late throws off your biological clock, which can lead to obesity, diabetes, and heart disease.

Myth: Alcohol can help you rest easy.

    ____ Alcohol may relax you so you nod off quicker, but studies show you'll wake up more and get less of deep sleep you need to feel rested.

A. You need 8 hours' sleep a night.

B. A lack of sleep can cause anxiety.

C. We take unscheduled naps during the weekend.

D. I've been a 6.5-hour sleeper my entire adult life.

E. Many people can't turn off their brains, but watching TV helps.

F. People commonly use alcohol to fall asleep, but it doesn't work.

G. You can't make up for too little sleep by sleeping more at weekends.