Jun 22, 2019
RAY: This guy has a new house built. As luck would have it, his entire backyard is just dirt, and he's planning on having a big Fourth of July celebration. So he goes to the local nursery, and he says to the guy, "Look, I've got to buy some grass seed, because it's almost June 1 and I've got to have this party on the Fourth of July weekend. I want a yard full of grass!"
Sod's too expensive. He says, "Well, how much is seed?" And they discuss various options, and then finally the fellow at the nursery says, "Hey! We have this new product. It just came in a few months ago; you may be interested in it. It's a plug of grass. It looks about the size of your fist. You plant this in your lawn in a central location, and every day it doubles in size. You only need one."
He says, "You mean, if I plant this thing on June 1, by June 30 I'll have a lawn?" And the guy says, "Well, according to my calculations, no problem. And then what you have to do is spray it with this arrester spray, so it doesn't subsume your car.”
And the customer says, "You're sure you did the math correctly?" The nursery guy says, "I'm telling you -- plant one of these and in 30 days, you'll have a full lawn in your backyard." And the customer says, "Great, but just to be on the safe side, I want two."
So, the question is: If in fact one would give him a lawn in 30 days, what day must he apply the arrester spray to stop it from subsuming his car, his garage and his kids if he uses two grass plugs?
RAY: Now, logic would tell you if you bought two, it would then be June 15, right? But the answer is, instead of his lawn being finished on June 30, it's done on June 29, because all it does is gain him one day. Because don't forget, when you plant one, the next day, how many do you have? Two, right?
Wrong, you don't really have two.You have double the size.
Which is what you get if you bought two of them. And what happens the next day? You've got four. So, all it does it lop off the first day. So that's the answer: he sprays it on June 29, and if he doesn't, then it eats his house.