Posted by MathsHelpNeeded on Thursday, August 27, 2009 at 6:34am.
Eleven people, 7 men and 4 women, successfully completed their study at the School of Astronautics. A team of 6 people needs to be selected from them for the next intergalactic travel. In how many ways can 6 astronauts be selected, if at least 2 women and 3 men must be in the teamH
This question was answered by Reiny and i was wondering how she got her andwer :
For at least 2 women and 3 men, the only cases would be
2W,4M = C(4,2) x C(7,4) = 6x35 = 210 , or
3W,3M = C(4,3) x C(7,3) = 4x35 = 140
for a total of 350 ways
I would like to know how you got the 35 in the 6 X 35 and the 4 X 35
- Maths - Reiny, Thursday, August 27, 2009 at 8:03am
Wow, this goes back quite some time.
C(n,r) = n!/(r!(n-r)!) , so
C(7,3) = 7!/(3!4!) = 35 , and
C(7,4) = 7!/(4!3!)
Most scientific calculators contain the functions C(n,r) and P(n,r)
they are probably written as nCr and nPr
Here is a page that explains the notation and difference between combination and permutation.
You might also google "Pascal's Triangle" to see a very interesting relationship between the values of C(n,r) and the rows of the triangle.
Look at the last row of this version of the triangle
Answer this Question
More Related Questions
- Maths - Eleven people, 7 men and 4 women, successfully completed their study at ...
- gr12 math - froma group of 6 ladies and 4 men, determine in how many ways a ...
- math - from a group of women and 4 men, determine in how many ways a committee ...
- Math - I'm really struggling with how to set this up: A company has 18 members ...
- math - You are forming 3 teams from 25 people. Team A has 8 Team B has 3 Team C ...
- statistics - To find out what people think, the Gallup Poll selected a random ...
- Algebra - There are 15 people to choose from for a nine-person batting order in ...
- math word problem - There are 10 women and 8 men in a club. How many different ...
- math - a committee of 5 people is to be selected from a group of 6 men and 9 ...
- maths - 95. Suppose that 387 people will travel on a space shuttle with room for...