254． A retailer sell red and white t-shirts in both medium and large size. The number of medium white sold is 3 times as many as large red sold. The number of medium white sold is 2 times that of large white. Total revenue of red is 80, total revenue of white is 190 Grand total is $1080. how much is the medium white ? (number are close, but not exactly accurate, just get the concept, number doesn’t matter).
255． {Sqrt(x)+ Sqrt(y) } / (Sqrt(x) -Sqrt(y)) - Sqrt(24)/ {Sqrt(x)^2- Sqrt(y)^2}, simply the above equation. 5 choices. Just use (a^2-b^2=(a+b)(a-b), you can easily identify the answer)
256． 6 balls, numbered 1-6, pick one at a time without replacement (exact words， faint again), the order doesn’t matter, what’s the possible combination
a. 10
b. 20
c. 30
d. 40
e. 50 这题搞了我很久，丢脸，大侠帮忙看看，数字因该准确，总之不上百
257． What is the reminder of x when it is divided by 9
a. Know the remainder of x when it is divided by 3
b. Know the remainder of x when it is divided by 3
258． N is a two-digit number, what’s the tens of n?
a. The tens of 2n =5
b. The tens of 2n=0
259． X increase annually by 20% in 1994 and 1995, Y increase by 40% in 1994 then by 1% of the amount of the previous year in 1995. which of the following must be true.
a. X-y<2
b. 0
260． xy>0
a. |x|=|y|
b. x^2=y
