Escape from the Well after a Horrible Fall

Last Problem:

During his walk every day, Ted Jones likes to exercise his dog, Chad, by throwing a Frisbee for him to retrieve. If Ted wants Chad to run as far as possible during the walk every day, what direction should Ted throw the Frisbee for Chad to retrieve?

Answer:

Ted Jones should throw the Frisbee backward so that his dog Chad will have to run the additional distance Ted walks while his dog retrieves the Frisbee.

Today’s Problem:

A frog falls into the bottom of a 20 meter well. In her struggle to get out, she advances 3 meters up the slimy walls of the well; during the night when she rests, the frog slips back 2 meters.

How many days will it take for the frog to escape from the well?

How to Exercise a Dog While Walking

Yesterday’s Problem:

A sealed bottle containing 48 flies is placed on a weight scale.

When does the scale register the heaviest weight:

When the flies are resting on the bottle of the bottle or when all 48 flies are in flight?

Answer:

The weight is the same in both instances. The weight depends on the mass of the bottle and its contents, and that does not change. When flies are in flight, their weight is transmitted to the bottle by air currents, especially the downdraft generated by moving wings.

Today’s Problem:

During his walk every day, Ted Jones likes to exercise his dog, Chad, by throwing a Frisbee for him to retrieve. If Ted wants Chad to run as far as possible during the walk every day, what direction should Ted throw the Frisbee for Chad to retrieve?

Flies in a Bottle

Last Question:

You have sealed the ninth of nine identical parcels of precisely equal weights, only to discover that your diamond ring has accidentally fallen into one of the packages.

You don’t want to unwrap every parcel. Can you work out how to find the parcel containing the ring with just two weightings of the parcels?

Answer:

Weight three parcels against three parcels. If one side is heavier than the other side, one of the three parcels on the heavier side must contain the ring. If both sides are equal in weight, the ring has to be in one of the three parcels that were not weighed.

From the group of three that you now know contains the ring, weigh one against the other. The heavier of the two now has the ring; if both are equal, the ring will be found in the unweighted parcel.

Today’s Problem:

A sealed bottle containing 48 flies is placed on a weight scale.

When does the scale register the heaviest weight:

When the flies are resting on the bottle of the bottle or when all 48 flies are in flight?