Question; sailing ships used to send messages with signal flags flown from their masts

Question

1. Sailing ships used to send messages with signal flags flown from their masts. How many different signals are possible with a set of four distinct flags is a minimum of two flags is used for each signal? Please explain how to do this question, I don't understand what to do.

Please provide detail on how the flags they are chosen those ways,

Also when the question says "with a set of four distinct flags is a minimum of two flags is used for each signal", do they mean that your given 4 flags and the minimum of flags for each signal is 2?

Answer 1

First of all, I think you do not have enough information: in particular how many masts.

However, if what is intended is the number of combinations of 4 things taken 2, 3 and 4 at a time, this answer is 11.

You should also know about a wonderful little book, well know to beginning actuarial students, called

"Choice and Chance" by Whitworth, published in the 1890s and still in print. He discusses this question at length.