[問題]GWD 03-30

[shine_allen]

M = {-6, -5, -4, -3, -2}
T = {-2, -1, 0, 1, 2, 3}
If an integer is to be randomly selected from set M above and an integer is to be randomly selected from set T above, what is the probability that the product of the two integers will be negative?

A. 0
B. 1/3
C. 2/5
D. 1/2
E. 3/5
Answer is D,How?

[yak167]

Since all the integers in M are negative, thus no matter what number is selected from M, as long as it is multipled by a POSITIVE number from T, the product will be negative, means only 1,2,3 can be selected.
So, D is the answer.

[schung0529]

Since all the integers in M are negative, thus no matter what number is selected from M, as long as it is multipled by a POSITIVE number from T, the product will be negative, means only 1,2,3 can be selected.
So, D is the answer.

我還是有點不懂
可以再講一下下嗎? 先謝謝囉

[hunnybobo]

M = {-6, -5, -4, -3, -2}
T = {-2, -1, 0, 1, 2, 3}
If an integer is to be randomly selected from set M above and an integer is to be randomly selected from set T above, what is the probability that the product of the two integers will be negative?

A. 0
B. 1/3
C. 2/5
D. 1/2
E. 3/5
Answer is D,How?

the product of the two integers will be negative?
表示從M,T兩集合中,選的二個數字其中一個要為負數
M全為負,所以從T中選出的數字一定要正的
6個中取3個==>1/2

[chris8888]

M = {-6, -5, -4, -3, -2} <== 5個negative
T = {-2, -1, 0, 1, 2, 3} <== 3個positive

negative * positive = negative
so 5 * 3 = 15

total = 5 * 6 = 30

15/30 = 1/2 answer : D