The members of a chess club are all ranked as beginner, intermediate or expert
The ratio of beginners to intermediates is 10: 3 and the ratio of intermediates to experts is 2 : 5.
The head of the club takes a sample of 82 members of the club so that the proportions of beginners, intermediates and experts in the sample are the same as the proportions in the whole club.
How many intermediates are in their sample?