[問題] GWD 17-20

[FionaV]

GWD 17-20

For any integers x and y, min(x,y) and max(x,y) denote the
minimum and the maximum of x and y, respectively.
For example, min(5,2) = 2 and max(5,2) = 5.
For the integer w, what is the value of min(10,w)?

(1) w = max(20,z) for some integer z
(2) w = max(10,w)

Ans: D

請問為什麼條件(1)也充分呢?

[zazer.lin]

不好意思...先幫您更正一下題目...

GWD 17-20

For any integers x and y, min(x,y) and max(x,y) denote the
minimum and the maximum of x and y, respectively.
For example, min(5,2) = 2 and max(5,2) = 5.
For the integer w, what is the value of min(10,w)?

(1) w = max(20,z) for some integer z
(2) w = max(10,w)

Ans: D

statement(1)
<i> z < 20
w = max(20, z) = 20, then min(10, w) = min(10, 20) = 10
<ii> z = 20
w = max(20, z) = 20, then min(10, w) = min(10, 20) = 10
<iii> z > 20
w = max(20, z) = z, then min(10, w) = min(10, z) = 10 .....(note z > 20)
By <i><ii><iii> statement(1) alone is sufficient

statement(2)
<i> w > 10
w = max(10, w) = w, then min(10, w) = 10 ........(because w>10)
<ii> w = 10
w = max(10, w) = 10, then min(10, w) = min(10, 10) = 10
<iii> w < 10
w = max(10, w) = 10, then min(10, w) = min(10, 10) = 10
By <i><ii><iii> statement(2) alone is sufficient

Therefore, the answer is (D)

[FionaV]

了解了
謝謝