From 6 positive numbers and 7 negative numbers, how many groups of 4 numbers, yielding a positive ...
From 6 positive numbers and 7 negative numbers, how many groups of 4 numbers, yielding a positive product, can be formed?
Answer/Solution
365
Steps/Work
The number of ways to choose 4 positive numbers is 6C4 = 15.
The number of ways to choose 4 negative numbers is 7C4 = 35.
The number of ways to choose 2 positive and 2 negative is 6C2*7C2 = 15*21 = 315.
The total number of groups is 15+35+315 = 365.
The answer is D.
The number of ways to choose 4 negative numbers is 7C4 = 35.
The number of ways to choose 2 positive and 2 negative is 6C2*7C2 = 15*21 = 315.
The total number of groups is 15+35+315 = 365.
The answer is D.