[填空题]
A market research survey asked 200 tetc1 41l9zevnv enagers for the number of minutes they(oclw7ax8gsaq- 9kz; 2igq 7v spend on their phones on a daily basis. The results were recorded in thex os i7(k ;wcaq79g zlv-aq28g following box-and-whisker diagram.
1. Write down the median.
The following incomplete table shows the distribution of the responses from these 200 teenagers. minutes
2. Complete the table.
3. (1) Write down the mid-interval value for the $80 (2) Using the table, calculate an estimate for the mean number of minutes spent on phones daily by these 200 teenagers. ≈ minutes
The 200 teenages were chosen for the survey by randomly selecting student ID numbers in a school, using a random number generator.
4. Identify the sampling method used.
