题干

为了提高学生写好汉字的积极性,某校组织全校学生参加汉字听写比赛,比赛成绩从高到低只分A、B、C、D四个等级.若随机抽取该校部分学生的比赛成绩进行统计分析,并绘制了如下的统计图表:

所抽取学生的比赛成绩情况统计表

成绩等级

A

B

C

D

人数

15

x

10

5

抽查学生占抽查

总数的百分比

m

40%

20%

10%

根据图表的信息,回答下列问题:

(1)本次抽查的学生共有____ 名;

(2)表中x和m所表示的数分别为:x=____ ,m=____ ,并在图中补全条形统计图;

(3)若该校共有1500名学生,请你估计此次汉字听写比赛有____ 名学生的成绩达到B级及B级以上?

 

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答案(点此获取答案解析)

50,20,30%,1050

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    Businesses are finding more uses for Virtual Reality (VR) as the technology develops. VR is no longer only for gaming or enjoyment. An American company called Blue Goji is using VR to improve one's health by making exercise more fun.

    Blue Goji has offices in Austin, the capital of Texas. The company showed its cardiovascular (心血管的) workout machine, called the Infinity treadmill (跑步机), at the recent South by Southwest festival, an event held every year in Austin.

    A person using the treadmill wears a virtual reality headset when exercising. Before starting, the user tightens a belt to prevent falls. Then, the user plays a VR game while running on the machine. The game can transport the user into the virtual world, where he or she can be racing against virtual people.

    Recently, Leonardo Mattiazzi tested the Infinity treadmill. Mattiazzi said he had a strong feeling to actually get running and do something that pushed his limits. He said the experience was more interesting than running inside the gym without actually going anywhere.

    Constam said the active use of virtual reality helps solve a common problem while wearing a VR headset. She noted that a lot of VR experiences cause motion sickness because people are in motion during the game, but not moving in real life. But when the user is moving on the treadmill and in the game, the chances of motion sickness are reduced.

    However, users who tested the treadmill while wearing the VR headset each had a different experience. Constam said there generally is a learning curve for VR. The first time users feel lost, but "the more you do it, the more you get used to it," she said. Mark Sackler was a first time user. He said he felt a little sick at one point during the game. But he thought the experience was surprisingly realistic.

    After carefully studying the users' experiences, Blue Goji plans to make the treadmill available to the public in 2019.