Brain Teaser

[silver914]

This one isn't that tough.

Say you want to make three pieces of toast, but your toaster is one of those oven style toasters so you lay the slices in there flat and it only holds two slices of bread at a time. One other caveat; your toaster will only brown one side of the bread at a time. To do the other side you have to flip the bread over. Each side takes 30 seconds to brown. How long does it take to make the toast.

 

[u21c3f6]

90 seconds

Joe.

 

[LT701]

Quote from silver914:

This one isn't that tough.

Say you want to make three pieces of toast, but your toaster is one of those oven style toasters so you lay the slices in there flat and it only holds two slices of bread at a time. One other caveat; your toaster will only brown one side of the bread at a time. To do the other side you have to flip the bread over. Each side takes 30 seconds to brown. How long does it take to make the toast.

i'd just get a new toaster

i cant think before i've had my morning coffee

 

[horribilicus]

A group of 2300 (two thousand + three hundred) people are selected at random.

What is the probability that at least one person in the group was born on January 1st, AND at least one person in the group was born on January 2nd, AND at least one person in the group was born on January 3rd, AND ..., AND at least one person in the group was born on December 31st?

In other words,

What's the probability that every possible day on the calendar, is the birthday of at least one person in the group?

(For simplicity, ignore leap day (Feb 29) birthdays)


You could reformulate the problem as follows. A dartboard is divided into 365 equal sized sections. 2300 darts are tossed at the dartboard, at random. What is the probability that each and every section among the 365 sections, was hit by at least one dart?

 

[horribilicus]

If you're tempted to apply Monte Carlo (MC) solution methods, beware that this problem converges relatively slowly. It's a perfectly valid way to get an answer, of course; just be sure you turn the crank a sufficient number of times. The closed-form solution provides greater accuracy in less time. Naturally.

 

[harry11]

Quote from silver914:

This one isn't that tough.

Say you want to make three pieces of toast, but your toaster is one of those oven style toasters so you lay the slices in there flat and it only holds two slices of bread at a time. One other caveat; your toaster will only brown one side of the bread at a time. To do the other side you have to flip the bread over. Each side takes 30 seconds to brown. How long does it take to make the toast.

Definitely 90 seconds.. 30 seconds for 1 side each. 30 more to get the 2nd side and the 1st side of the 3rd slice. and another 30 to complete the other 2.

 

[harry11]

this 1 is really hard- u have a 3 oz bottle and a 5 oz bottle.
how do you get 4 oz of water into the 5 oz bottle? u cannot put 4 oz straight into the 5 oz bottle obviously cause u cant measure..

 

[silver914]

It's not that hard. First fill the 5 oz. bottle. From that fill the 3 oz. bottle, then empty it and that leaves 2 oz. in the 5 oz. bottle. Transfer the 2 oz. from the 5oz. bottle to the 3 oz. bottle. Fill the 5 oz. bottle again, then pour just enough from the 5 oz. bottle to fill the three oz. bottle (which already has 2 oz. in it) and that leaves 4 oz. in the 5 oz. bottle.

Next.

Edit: Okay here it is.

The roof of a barn lies east to west, in other words one pitch faces to the north and the other pitch to the south. A rooster lays an egg on the ridge. Which side of the barn will the egg roll down, to the north or to the south?

 

[maxpi]

Quote from silver914:

This one isn't that tough.

Say you want to make three pieces of toast, but your toaster is one of those oven style toasters so you lay the slices in there flat and it only holds two slices of bread at a time. One other caveat; your toaster will only brown one side of the bread at a time. To do the other side you have to flip the bread over. Each side takes 30 seconds to brown. How long does it take to make the toast.

120 sec plus time for flipping


Edit... nope, it's 90 secs if you are smart and in a big hurry

 

[silver914]

Joe got it right. 90 seconds is the correct answer.