<image>The following problem involves height surveys of seventh-grade students in a certain district (unit: cm). A random sample of students was taken, and the data was processed and divided into seven groups (each group contains only the minimum value, not the maximum value), resulting in the partial charts below: \frac{    }
Based on the information above, answer the following questions:
(1) How many students were surveyed for their height in the district? Answer: ____;
(2) The median height of the surveyed students falls into the ____ group;
(3) The central angle of the sixth group segment in the pie chart is ____ degrees;
(4) If there are 5000 seventh-grade students in the district, then approximately ____ students are no shorter than 160 cm;
(5) Can this data be used to estimate the height of first-year high school students in the district? Why?