During the first semester of the school, Avery and Eitan spent a combined 60 hours practicing the violin for an orchestra concert. If Avery practice 15 hours less than twice the amount than Eitan did, how many hours did each person practice playing the violin?

Avegetable garden and a surrounding path are shaped like a square that together are 11ft wide. the path is 2ft wide. find the total area of the vegetable garden and path

These tables represent a quadratic function with a vertex at (0, -1). what is the average rate of change for the interval from x = 9 to x = 10?

Agroup of student volunteers participates in a study designed to assess several behavioral interventions for improving output in a repetitive task. prior to the beginning of the study, all volunteers unknowingly observed, and their output is measured. at the beginning of the study, prior to any intervention, the volunteers perform the same task under the observation of a study administrator, and their overall output increases. which of the following terms describes this phenomenon? a. simpson's paradox b. hawthorne effect are d. novelty effect d. pygmalion effect e. observer-expectancy effect