问题 问答题 计算题

已知某完全竞争的成本不变行业中的单个厂商的长期总成本函数LTC=Q3-12Q2+40Q。试求:(1)当市场商品价格是P=100,厂商实现MR=LMC时的产量,平均成本和利润;(2)该行业长期均衡时的价格和单个厂商的产量;(3)市场的需求函数为Q=660-15P时,行业长期均衡时的厂商数量。

答案

参考答案:

(1)LTC′=LMC=3Q2-24Q+40=MR=P=100

此时,3Q2-24Q+60=0,∴Q=10或Q=-2(舍去);LAC=Q2-12Q+40=20;利润=(P-LAC.Q=800

(2)LAC最低点=PLAC′=2Q-12=0,∴Q=6LAC最低点=4

即该行业长期均衡时的价格为4,单个厂商的产量为6

(3)成本不变行业长期均衡时价格是市场均衡价格,所以市场需求为Q=660-15×4=600,则厂商数量为600/6=100

阅读理解

阅读理解。

     Last week my youngest son and I visited my father at his new home in Tucson, Arizona. He moved there

a few years ago, and I was eager to see his new place and meet his friends.

     My earliest memories of my father are of a tall, handsome successful man devoted to his work and family,

but uncomfortable with his children. As a child I loved him; as a school girl and young adult I feared him and

felt bitter about him. He seemed unhappy with me unless I got straight A's and unhappy with my boyfriends

if their fathers were not as "successful" as he was.

     Whenever I went out with him on weekends, I used to struggle to think up things to say, feeling on guard.

     On the first day of my visit, we went out with one of my father's friends for lunch at an outdoor cafe. We

walked along that afternoon, did some shopping, ate on the street table, and laughed over my son's funny facial

expressions. Gone was my father's critical (挑剔的) air and strict rules. Who was this person I knew as my

father, who seemed so friendly and interesting be around? What had held him back before?

     The next day my dad pulled out his childhood pictures and told me quite a few stories about his own

childhood. Although our times together became easier over the years, I never felt closer to him at that moment.

After so many years, I'm at last seeing another side of my father. And in so doing. I'm delighted with my new

friend. My dad, in his new home in Arizona, is back to me from where he was.

1. What does the author think of her father after her visit to Tucson?

A. He was silent most of the time.

B. He was too proud of himself.

C. He did not love his children.

D. He expected too much of her.

2. When the author went out with her father on weekends, she would feel _____.

A. nervous

B. sorry

C. tired

D. Strict and hard-working

3. What does the author think of her father after her visit to Tucson?

A. More critical.

B. More talkative.

C. Gentle and friendly.

D. Strict and hard-working.

4. The underlined words "my new friend" in the last paragraph refer to _____.

A. the author's son

B. the author's father

C. the friend of the author's father

D. the café owner

判断题