WAEC - Further Mathematics (2021 - No. 26)
A committee consists of 6 boys and 4 girls. In how many ways can a sub-committee consisting of 3 boys and 2 girls be formed if one particular boy and one particular girl must be on the sub-committee?
120
80
56
30
Paliwanag
The required committee can be formed in
(a boy and a girl are already part of the committee so we need two more boys and a girl).
\(^{5}C_{2}\) * \(^{3}C_{1}\) = \(\frac{5 * 4*3*2*1}{3* 2 * 2*1}\) * \(\frac{ 3* 2* 1}{ 2 * 1}\)
10 * 3 = 30ways.