22. At their respective rate, pump A can fill 1/2 of a tank in 3 hours, and pump B can fill 2/3 of the tank in 6 hours. Working together, how many hours will it take A and B to fill the tank? 23. The value of 1/11+1/12+1/13+...+1/20 will be A. Less than 1/3 B. Less than 1/2 C. Greater than 1/2 D. Greater than 2/3 E. … 24. Maria invested a certain amount of money at r percent compounded annual interest rate. r=? 1). She earned an interest of $200 in the first year. 2). She earned an interest of $220 in the second year. 25. In the xy-plane, line L passes through point (1,p). Does L have a positive slope? 1). L passes through point (-p, 13) 2). L passes through point (0,1) 26. In a class of 120 students, 80 can speak English, 70 can speak Spain, 60 can speak French. If every student in the class can speak at least one of the languages, at least how many of students in class can speak all the three languages? 27. At the same time, Ken invested x dollars at compounded annual interest rate of 4%, and Marlon invested y dollars at compounded annual interest rate of 6%. x/y=? 1). At the end of the second year, Ken and Marlon earned same amount of interest. 2). At the end of the second year, Ken earns an interests of $400, and Marlon eared an interest of $500. 28. A’s salary for any week is $600 plus 5% of the portion of A’s sales above $2000 for that week. B’s salary for any week is 10% of his sales for that week. For what amount of sales in a certain week would A and B earn the same salary? 29. Which of points (4,6) and (-5,5) is closer to the origin? 30. In a certain test, a student must answer 8 out of 10 questions. How many choices are there if at least 4 of the first five questions must be answered? 31. If x=3y, is x^2>y^2? 1). y+x<y*x 2). X^2=9y^232. A is cycling around a track at a speed of 15 mph. B starts at the same time at a speed of 12 mph. If A and B move at the same direction and the track is 1/2 mile long, how many minutes after they start will A pass B if? 33. What is the tens’ digit of integer X? 1). The tens’ digit of X-9 is 1 2). The hundreds’ digit of 10X is 2 34. A fish tank is half full of water. If 10 gallons of water were added, the tank would be 7/8 full. What is the capacity of the tank? 35. The average of A, B, C, D, and E is C, and C=A+B. In terms of C, D+E=? 36. Terry receives 10z coins in addition to what she already had. She now has 5y+1 times as many coins as she had originally. In terms of y and z, how many coins did she have originally? 37. The price of a item decline by 67% every 6 months. At the rate, approximately how many years will it take for the $81 item to reach $1? 38. Set A has 20 numbers and B has 40 numbers. Is the range of B greater than 45? 1). The range of A and B combined exceeds 50 2). Range of B is greater than range of A 39. Sequence 2, 7, 22,…after the first three terms, each term is three times the previous term plus 1, a(n+1)=3an + 1. What is the sum of tens digit and tens digit of the 35 term?
[此贴子已经被作者于2006-10-10 22:59:11编辑过] | 
