BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

distinct numbers

Expert replies
by shashank.ism » Sat Feb 20, 2010 1:39 pm
There are nine distinct numbers of which five numbers are positive and four numbers are negative. Three numbers are chosen at random and the product of these numbers is found. How many of these products are positive?

A) 48
B) 300
C) 40
D) 90
E) None of these

CA is C
My Websites:
www.mba.webmaggu.com - India's social Network for MBA Aspirants

www.deal.webmaggu.com -India's online discount, coupon, free stuff informer.

www.dictionary.webmaggu.com - A compact free online dictionary with images.

Nothing is Impossible, even Impossible says I'm possible.
Join the discussion
Source: — Problem Solving |

by ajith » Sat Feb 20, 2010 8:58 pm
shashank.ism wrote:There are nine distinct numbers of which five numbers are positive and four numbers are negative. Three numbers are chosen at random and the product of these numbers is found. How many of these products are positive?

A) 48
B) 300
C) 40
D) 90
E) None of these

CA is C
The product is positive if

1) Two numbers are negative and one positive - select 2 negative num are 1 positive - 4C2*5C1 = 6*5 =30
2) All the three numbers are positive - 5C3 = 5*4/2 = 10

Total no of ways = 30+10 =40
Always borrow money from a pessimist, he doesn't expect to be paid back.
Join the discussion