Saturday Photographer Puzzle 1

A photographer takes about 15 seconds to line up a group of people and take their photo. Faced with a group of 4 people, and a little extra time, he decides to take their photo in every arrangement possible (this guy always lines them up in 1 row, and never leaves gaps). How long will it take to take all the photos? Guess before you do the math, always more fun that way. ;)

Four more people come along, so he decides to take pictures of the whole group, again in every possible one-row, no-gap arrangement. How long will this take? (guess first!)

Finally, four more people come along. Now with twelve people, how long will it take for him to take all the photos?

Thanks to Jim Matthews for these. I don’t know where he got them from, or if he made them up.