Let S be the sample space and E be the event of selecting 1 girl and 2 boys.
| Then, n(S) |
= Number ways of selecting 3 students out of 25 |
|
= 25C3 ` |
|
| = |
(25 x 24 x 23) |
| (3 x 2 x 1) |
|
|
= 2300. |
| n(E) |
= (10C1 x 15C2) |
|
| = |
[ |
10 x |
(15 x 14) |
] |
| (2 x 1) |
|
|
= 1050. |
| ∴ P(E) = |
n(E) |
= |
1050 |
= |
21 |
. |
| n(S) |
2300 |
46 |
