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Facial shaving brushes are either bulb-shaped or fan-shaped. an experiment is to be conducted to determine whether the lather thickness is the same for both types of shaving brushes. in previous studies, it was determined that shaving brush size (small, medium, large) is associated with lather thickness, but shaving brush type (wolf whiskers, maggard razors, frank shaving, and so on) is not associated with lather thickness. how could the experiment best be conducted? by blocking on shaving brush size by blocking on shaving brush type by blocking on shaving brush shape by blocking on lather thickness without blocking

1  2  3  4  5  6  7  8  9  10  below is a chart representing portions of résumés from three applicants.                                      excerpts from résumés of three job applicants  job expertise    applicant 1  developed effective techniques for keeping order in the classroom    applicant 2  effectively designed a program for new employees    applicant 3  took many courses in child psychology and human development      which  best  explains the applicants’ careers?

What drifted apart millions of years ago to create two different worlds