题干

“中国梦”关乎每个人的幸福生活,为进一步感知我们身边的幸福,展现成都人追梦的风采,我市某校开展了以“梦想中国,逐梦成都”为主题的摄影大赛,要求参赛学生每人交一件作品.现将参赛的50件作品的成绩(单位:分)进行统计如下:

等级

成绩(用s表示)

频数

频率

A

90≤s≤100

x

0.08

B

80≤s<90

35

y

C

s<80

11

0.22

合 计

50

1

请根据上表提供的信息,解答下列问题:

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    A new phone app uses shaking from smartphones to warn people about earthquakes. The new app is called MyShake, which is the work of four researchers at the University of California. Berkeley.

    Smartphones are equipped with accelerometers(加速器). MyShake uses phone accelerometers to measure seismic (地震的) activity. It has been programmed to know the difference between normal activity and earthquake movement. The software developers say their app is right 93 percent of the time. A smartphone sends seismic information to the app developers. If the developers receive several warnings from one area, it recognizes that an earthquake may be taking place or will take place soon. Using information sent from the app, the network then judges the location and strength of the quake in real time. MyShake can record 5.0 earthquake at distances of 10 kilometers or less.

    MyShake uses very little power, according to its developers. Only when seismic activity is sensed by the app does it become active and sends data to the network. The app works best when your phone is resting on a flat surface, like a table.

    The developers hope that MyShake can add to information collected by the U.S Geological Survey. That U.S agency has created the Earthquake Early Warning System, also known as the EEW. The EEW has used sensors for measuring quakes in many areas. In places where no such equipment exists, MyShake may be the only method of early quake detection (发现). The app also shows ways to stay safer during an earthquake. The developers say it will become more effective as more people use it.

    The developers say they hope to add a feature that will warn people about possible tsunami after an earthquake.