Two magazines recently listed the best cities to live in. Here are two of the cities listed as "the world's best."

    SAN JOSE, COSTA RICA The city has comfortable weather all year round (15℃ to 26℃). Housing is not very expensive in San Jose. Also, many of the city's older neighborhoods are very beautiful and have small hotels and cafés. Beautiful mountains are around the city. Lots of people go sightseeing there every year. But air pollution is a problem in the city center.

    HONG KONG, CHINA This lively city—once a small fishing village—is today an international business center. It is an interesting mix of East and West, old and new. Modern tall buildings are next to small temples (庙宇). Popular nightclubs are close to traditional teahouses. Busy people fill the streets at all hours of the day. But outside the city, there are parks for walking or relaxing. Hong Kong is famous for its wonderful native dishes. There's also food from Europe, North America, and other parts of Asia. However, this small city has a large population of nearly seven million! That's why housing is often very expensive. Traffic and air pollution are also a problem.

已知正弦函数$y=\sin x$的图象关于点$\left(\theta ,0\right)$对称,则$\cos \theta =$(      )

该社团将该校区在2016年100天的空气质量指数监测数据作为样本，绘制的频率分布直方图如图，把该直方图所得频率估计为概率．

（Ⅰ）请估算2017年（以365天计算）全年空气质量优良的天数（未满一天按一天计算）；

（Ⅱ）该校2017年6月7、8、9日将作为高考考场，若这三天中某天出现5级重度污染，需要净化空气费用10000元，出现6级严重污染，需要净化空气费用20000元，记这三天净化空气总费用为X元，求X的分布列及数学期望．