想請教一個數 學問題
Q33:
A photographer
will arrange 6 people of 6 different heights
for photograph by placing them in two rows of three so that
each person in the first row is standing in front of someone
in the second row. The heights of the people within each row
must increase from left to right, and each person in the second
row must be taller than the person standing in front of him or her.
How many such arrangements of the 6 people are possible?
A. 5
B. 6
C. 9
D. 24
E. 36
答案是A 不清楚怎麼得到的
想請教一下
謝謝^^
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 140.120.210.143