An athletic director wants to buy soccer balls and footballs. Each soccer ball costs $15. Each football costs $20. The director can spend no more than $150 in all. Write an inequality to model the situation, where x is the number of soccer balls and y is the number of footballs.

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