Scientists use different types of models to analyze the structure of ecosystems. which characteristic is seen in a biomass pyramid, but not in a numbers pyramid?
the total number of trophic levels in an ecosystem
living matter found at each trophic level in an ecosystem
energy available at each trophic level in an ecosystem
organisms found at each trophic level in an ecosystem

Alyeska services company, a division of a major oil company, provides various services to the operators of the north slope oil field in alaska. data concerning the most recent year appear below: sales $18,000,000 net operating income $6,300,000 average operating assets $35,200,000 1. compute the margin for alyeska services company. (round your answer to 2 decimal places.) 2. compute the turnover for alyeska services company. (round your answer to 2 decimal places.) 3. compute the return on investment (roi) for alyeska services company. (round your intermediate calculations and final answer to 2 decimal places.)

Areal estate agent is considering changing her cell phone plan. there are three plans to choose from, all of which involve a monthly service charge of $20. plan a has a cost of $.42 a minute for daytime calls and $.17 a minute for evening calls. plan b has a charge of $.52 a minute for daytime calls and $.15 a minute for evening calls. plan c has a flat rate of $80 with 275 minutes of calls allowed per month and a charge of $.38 per minute beyond that, day or evening.a. determine the total charge under each plan for this case: 150 minutes of day calls and 70 minutes of evening calls in a month. (do not round intermediate calculations. round your answer to 2 decimal places. omit the "$" sign in your response.)c. if the agent will use the service for daytime calls, over what range of call minutes will each plan be optimal? (round each answer to the nearest whole number.include the indifference point itself in each answer.)d. suppose that the agent expects both daytime and evening calls. at what point (i.e., percentage of total call minutes used for daytime calls) would she be indifferent between plans a and b?

In the 1970s, kmart used blue light specials to encourage customers to flock to a particular department having a temporary sale. a spinning blue light activated for approximately 30 seconds, and then an in-store announcement informed shoppers of the special savings in the specific department. over time, loyal kmart shoppers learned to flock to the department with the spinning blue light before any announcement of special savings occurred. if kmart was employing classical conditioning techniques, what role did the spinning blue light play?