[填空题]
A market research survey ;8jev7or2 j,ter crt 1asked 200 teenagers for the number *qk,sb8gw + g)2g-ctpg:t d guof minutes they spend on their phones on a daily basis. The results were recorded in the following box-and-whisker di2 *b-t cwgsgd:tupqg, g8)gk+agram.
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.
