46.求1/(根号(n+1)－根号n)?
根号(n+1)+根号n

47. A work performed at constant rate, it needs 4 workers to produce x units in 6 days, and how many workers are needed to produce 3x units in 4 days?

48. A square with points (1,1),(-1,1),(-1,-1)&(1,-1), ask the probability of point P(x,y) within the square where x^2+y^2=1?

49. 求P^r？
(1)P=1
(2)r=1

50. 一线段，依次P.Q.R.S点，已知PS＝20， 求QR
(1) PQ+RS=?
(2) PR=?, QS=?

51. Among the scientists attending the meeting, 80% are dental scientists(具体不记得了，不过只是一个指代，不影响解题), and 75% of these dental scientists are native American, ask the percentage of non-dental scientists who are native American.
(1)The total number of the scientists are 250
(2)The percentage of native Amercians among scientists are 75%

52.一柱形图，分别是93, 94，95，96年retail business的revenue(in billions of dollars), 94年为?95年为10, a store in 94 takes ?% in 1994 and 2.5％in 1995, ask the percentage of increase of the store from 1994 to 1995?

53. [x]表示小于或者等于X的integer, 当x=-5/2时，求[x]?

54.求x (1)X^2>2y
(2)X^3 E

55.j,k,m are from 0~9 inclusive, and T=10j+1000k+100m, 求unit digit of T?
(A)0,(B)1,(C)j,(D)k,(E)m

56.people own computers: IBM: ?人, Apple:85人 , Dell: ?人, Compaq: 77人, 和另外一个什么牌子的?人. Ask at most how many people could own both Apple and Compaq?

57.Pick 6 from 9 different chairs, pick 2 from 3 different tables,ask how many more selections of chairs than those of tables?

58.A series 1/2,1/4,1/8,1/16,1/32, each one is half of the one before, ask the range of the 10th number?

59.The factors of X are the prime factors of 770 and has only one prime factor that is not a factor of 770, ask the least possible ratio of x/770?

60.A plane travels from A to B in 3 hours at an average speed of 400 miles and the next day, it travels at an average speed of 450 miles, ask how many minutes less does it spend the next day?