Question

A box contains five balls numbered 1, 2, 3, 4, 5. Three balls are drawn randomly at the same time from the box.
(i) By listing all possible outcomes (123, 124, etc.), find the probability that the sum of the three numbers drawn is an odd number.
The random variable L denotes the largest of the three numbers drawn.
(ii) Find the probability that L is 4.

Answer 1

The possible outcomes could be:{123,124,125,134,135,145,234,235,245,345}
Their sums are as follows respectively:{6,7,8,8,9,10,9,10,11,12}=7
The odd sums are{7,9,11}=3
the probability of the sum being odd is 3/7
b.The number of outcomes are 10
 the number of outcomes in which L is 4 are 3
So the probability of L being 4 is 3/10