GMAT數(shù)學(xué)備考資料：費(fèi)費(fèi)數(shù)學(xué)寶典詳解版
11、S=，T=。One number is selected from S, and the other number is selected from T. What is the probability that the product of the two numbers is negative?
【答案】1/2
【思路】C5 1C3 1 / C5 1C6 1=1/2
12、
What is the function of the curve above?
y = x^3 - x^2
y = - x^3 + x^2
y = - x^3 +x
y = x^3 - x
y = x^3 + x
【答案】
【思路】根據(jù)圖形可以知道應(yīng)該找與X軸有三個(gè)交點(diǎn)，也就是y等于0時(shí)可以解出三個(gè)實(shí)根的方程。排除、、，因?yàn)橹挥袃蓚€(gè)實(shí)根，也是有兩個(gè)實(shí)根，只有一個(gè)實(shí)根，只有是對(duì)的。又可以通過增減函數(shù)來排除，圖形告訴我們X向正無窮方向增加，Y的值也隨之增加，從某點(diǎn)開始為增函數(shù)，再看方程明顯從某點(diǎn)開始后為減函數(shù)，因此是對(duì)的。
分頁標(biāo)題#e#
13、0-50中，被3整除余1的數(shù)有多少個(gè)?
【答案】有17個(gè)
【思路】0=3x+1=50 x=0.16
14、N is the sum of the first K consecutive positive integers, where 101=150. What is the sum of 1/N?
【答案】2
【思路】把first consecutive 理解為是從1開始到k 的數(shù)列。
N=K/2
1/N=2/K=2 1/K
因?yàn)?/K=1/K 1/
所以 2/K=2 =2
15. There are six cards each with a number from 1 to 6. Draw one card randomly and then put it back into a bowl. If one card is to be drawn randomly, and the sum of two cards is 8, whats the probability that the card is 5?
【答案】2/5
【思路】因放回，兩張cards之和=8有5種可能，2 6，6 2，3 5，5 3，4 4，其中出現(xiàn)5的可能有2種。
11、S=，T=。One number is selected from S, and the other number is selected from T. What is the probability that the product of the two numbers is negative?
【答案】1/2
【思路】C5 1C3 1 / C5 1C6 1=1/2
12、
What is the function of the curve above?
y = x^3 - x^2
y = - x^3 + x^2
y = - x^3 +x
y = x^3 - x
y = x^3 + x
【答案】
【思路】根據(jù)圖形可以知道應(yīng)該找與X軸有三個(gè)交點(diǎn)，也就是y等于0時(shí)可以解出三個(gè)實(shí)根的方程。排除、、，因?yàn)橹挥袃蓚€(gè)實(shí)根，也是有兩個(gè)實(shí)根，只有一個(gè)實(shí)根，只有是對(duì)的。又可以通過增減函數(shù)來排除，圖形告訴我們X向正無窮方向增加，Y的值也隨之增加，從某點(diǎn)開始為增函數(shù)，再看方程明顯從某點(diǎn)開始后為減函數(shù)，因此是對(duì)的。
分頁標(biāo)題#e#
13、0-50中，被3整除余1的數(shù)有多少個(gè)?
【答案】有17個(gè)
【思路】0=3x+1=50 x=0.16
14、N is the sum of the first K consecutive positive integers, where 101=150. What is the sum of 1/N?
【答案】2
【思路】把first consecutive 理解為是從1開始到k 的數(shù)列。
N=K/2
1/N=2/K=2 1/K
因?yàn)?/K=1/K 1/
所以 2/K=2 =2
15. There are six cards each with a number from 1 to 6. Draw one card randomly and then put it back into a bowl. If one card is to be drawn randomly, and the sum of two cards is 8, whats the probability that the card is 5?
【答案】2/5
【思路】因放回，兩張cards之和=8有5種可能，2 6，6 2，3 5，5 3，4 4，其中出現(xiàn)5的可能有2種。
