Some hotels charge by number of rooms and number of adults, and some hotels charge by number of rooms only.

Suppose the cost of operating a 75 room hotel for a night is $6,000 and there are 5 empty rooms for tonight. If the marginal cost of operating one room for one night is $40, the hotel manager should rent one of the empty rooms only if a customer is willing to pay

A．more than ＄40, as the average benefit will exceed the marginal cost．

B．more than ＄40, as the marginal benefit will exceed the marginal cost．

C．more than ＄80, as the average benefit will exceed the marginal cost．

D．more than ＄80, as the marginal benefit will exceed the marginal cost．

The audience _______ dressed in a variety of ways, some in suits and dresses, some in jeans.

A.is

B.has

C.are

D.have

Passage 5 The high-tech world of clocks and schedules, computers and programs was supposed to free us from a life of toil and deprivation, yet with each passing day the human race becomes more enslaved, exploited, and victimized. Millions starve while a few live in splendor. The human race remains divided from itself and severed from the natural world that is its primordial community. We now orchestrate an artificial time world, zipping along the electronic circuits of silicon chips, a time world utterly alien from the time a fruit takes to ripen, or a tide takes to receded. We have sped ourselves out of the time world of nature and into a fabricated time world where experience can only be simulated but no longer savored. Our weekly routines and work lives are punctuated with artificial rhythms, the unholy union of perspective and power. And with each new electric dawn and dusk, we grow further apart from each other, more isolated and alone, more in control and less self-assured. -- From “Time Wars” by Jeremy Rifkin The author’s first paragraph primarily serves to:

A、describe how humans have split from the natural world and have embraced technology.

B、identify the primary methods humans use to organize their lives.

C、criticize technology because it causes humans to turn from the natural world.

D、illustrate the ways in which humans are exploited by technology.

Passage 3 The high-tech world of clocks and schedules, computers and programs was supposed to free us from a life of toil and deprivation, yet with each passing day the human race becomes more enslaved, exploited, and victimized. Millions starve while a few live in splendor. The human race remains divided from itself and severed from the natural world that is its primordial community. We now orchestrate an artificial time world, zipping along the electronic circuits of silicon chips, a time world utterly alien from the time a fruit takes to ripen, or a tide takes to receded. We have sped ourselves out of the time world of nature and into a fabricated time world where experience can only be simulated but no longer savored. Our weekly routines and work lives are punctuated with artificial rhythms, the unholy union of perspective and power. And with each new electric dawn and dusk, we grow further apart from each other, more isolated and alone, more in control and less self-assured. -- From “Time Wars” by Jeremy Rifkin The author’s first paragraph primarily serves to:

A、identify the primary methods humans use to organize their lives.

B、criticize technology because it causes humans to turn from the natural world.

C、illustrate the ways in which humans are exploited by technology.

D、describe how humans have split from the natural world and have embraced technology.

Suppose that the cost of a gallon of heating oil will either be $0.90 or $1.10 in six months. The current price is $1.00 per gallon. (1) What are the risks faced by a reseller of heating oil that has a large inventory on hand? What are the risks faced by a large user of heating oil with a very small inventory? (2) How can these two parties use the heating oil futures market to reduce their risks and lock in a price of $1.00 per gallon? Assume each contract is for 50,000 gallons and they each need to hedge 100,000 gallons. (3) Can you say that each party has been made better off? Why or why not?

A coin is ?ipped twice. Let Y =number of heads obtained, when the probability of a head for a ?ip equals π. a. Assuming π =0.50 , specify the probabilities for the possible values for Y, and ?nd the distribution’s mean and standard deviation. b. Find the binomial probabilities for Y when π equals (i) 0.60, (ii) 0.40. c. Suppose you observe y =1 and do not know π. Calculate and sketch the likelihood function. d. Using the plotted likelihood function from (c), show that the ML estimate of π equals 0.50.