Suppose it starts snowing in the morning and continues steadily throughout the day. A snow cleaning mobile that removes snow at a constant rate starts plowing at noon. It plows 2 miles in the first hour, and 1 mile in the second. What time did it start snowing?

Donald is studying the eating habits of all students attending his school. he samples the population by dividing the students into groups by grade level and randomly selecting a proportionate number of students from each group. he then collects data from the sample. which type of sampling is used? select the correct answer below: systematic sampling convenience sampling stratified sampling cluster sampling