• May 23rd 2012, 12:44 PM
neil12
In a class of 20 pupils, 7 are left-handed and 13 are right-handed. Five pupils are selected at random from the class (the order is not important).

Find the probability that the sample of 5 will include 2 or fewer who are left-handed.

Thanks - please show me how you worked it out.
• May 23rd 2012, 12:55 PM
Plato
The probability of exactly two left-handed is $\frac{\binom{7}{2}\binom{13}{3}}{\binom{20}{5}}$.