#20
Tom, Jane, and Sue each purchased a new house. The average (arithmetic mean) price of the three houses was $120,000. What was the median price of the three houses?
(1) The price of Tom’s house was $110,000.
(2) The price of Jane’s house was $120,000.
答案是B....不懂,題目也沒說是照買的價格順序排的壓~~
#25
If the sequence x1, x2, x3, …, xn, … is such that x1 = 3 and xn+1 = 2xn – 1 for n ≥ 1, then x20 –x19 =
A.219
B.220
C.221
D.220 - 1
E.221 - 1
答案是A,算了半天頭都昏了.....
之前的說明看不太懂,可否再告知呢?感謝 @@@