In 1974, the U. S. Department of Transportation commissioned to create a master set of thirty-four passenger- and pedestrian-oriented symbols for use in transportation facilities. This effort represented an important first step toward the goal of unified and effective graphic communications transcending cultural and linguistic barriers in a shrinking world. A 225-page book published by the Department of Transportation provides invaluable information about the design and evaluation process used to arrive at this system.

Which statement best describes evidence of a mulitcultural mix in east africa? a. because of what he learned during his pilgrimage to mecca, mansa musa was able to build a center of islamic scholarship. b. the traders of ghana brought back with them slaves from the mediterranean who taught the ghana rulers about christianity. c. clans were made up of lineages that were descendants of multiple ancestors from different regions of africa. d. swahili became a language made up of words spoken by traders along the coast of the indian ocean.

According to the federal regulations, which of the following studies meets the definition of research with human subjects? a study of twenty 4th grade classrooms in which researchers ask the schools to systematically vary the time of day reading is taught, and collect weekly assessments of reading comprehension for each child over a three-month period.the collection of data, by a playground designer hired by the superintendent of schools, about the physical dimensions of school playgrounds, presence of fencing, and the kinds of equipment currently provided.a feasibility study for implementing a year-round school program, focusing on economic issues such a facilities utilization and transportation costs.an analysis of aggregate data comparing statewide high school graduation rates provided by the state department of public instruction, using county tax information.

What is the rule relating the ratio of marginal utility to prices of two goods at the optimal choice? explain why, if this rule does not hold, the choice cannot be utility-maximizing.