WSJ puzzles for this weekend

[Quix0te]

I confess that over the years, approximately half of these puzzles are over my head, another 25% i know how to solve but don't wish to dedicate the time needed to do it and the remaining 25% I can solve quite quickly. This weekend's puzzles are quite hairy....

Varsity Math Week 140


May 17, 2018 2:22 pm ET
21 COMMENTS

PHOTO: LUCI GUTIERREZ




The coach provides these two reasoning problems to prepare the math team.


Burning Ropes

You have two ropes and some matches. The ropes burn irregularly like fuses when lit at either end. The first rope burns in e = 2.71828…hours and the second rope burns in √2 = 1.414213… hours.

Produce a time interval as close as possible to 1 hour.



Nick’s Birthday
A while back, Nick stated: “Sometime during last year, I was still 21; in two days I’ll be in my 25th year.”

What day of the year is Nick’s birthday and on what day of the year is he speaking?

 

[TheOriginalHappyGoat]

I confess that over the years, approximately half of these puzzles are over my head, another 25% i know how to solve but don't wish to dedicate the time needed to do it and the remaining 25% I can solve quite quickly. This weekend's puzzles are quite hairy....

Varsity Math Week 140


May 17, 2018 2:22 pm ET
21 COMMENTS

PHOTO: LUCI GUTIERREZ




The coach provides these two reasoning problems to prepare the math team.


Burning Ropes

You have two ropes and some matches. The ropes burn irregularly like fuses when lit at either end. The first rope burns in e = 2.71828…hours and the second rope burns in √2 = 1.414213… hours.

Produce a time interval as close as possible to 1 hour.



Nick’s Birthday
A while back, Nick stated: “Sometime during last year, I was still 21; in two days I’ll be in my 25th year.”

What day of the year is Nick’s birthday and on what day of the year is he speaking?

Still working on #1. Answer to #2.

Spoiler: Spoiler

#2 - His birthday is January 2nd, and he is speaking on December 31. Last year, on January 1st, he was 21. The next day he turned 22. This year, he turned 23. In two days, he'll turn 24, which is the beginning of his 25th year.

 

[TheOriginalHappyGoat]

I confess that over the years, approximately half of these puzzles are over my head, another 25% i know how to solve but don't wish to dedicate the time needed to do it and the remaining 25% I can solve quite quickly. This weekend's puzzles are quite hairy....

Varsity Math Week 140


May 17, 2018 2:22 pm ET
21 COMMENTS

PHOTO: LUCI GUTIERREZ




The coach provides these two reasoning problems to prepare the math team.


Burning Ropes

You have two ropes and some matches. The ropes burn irregularly like fuses when lit at either end. The first rope burns in e = 2.71828…hours and the second rope burns in √2 = 1.414213… hours.

Produce a time interval as close as possible to 1 hour.



Nick’s Birthday
A while back, Nick stated: “Sometime during last year, I was still 21; in two days I’ll be in my 25th year.”

What day of the year is Nick’s birthday and on what day of the year is he speaking?

Okay! I figured out #1, too. That was a really good one.

Spoiler: Spoiler

Light one end of the e rope and both ends of the √2 rope. When the √2 rope burns out, approx. .7 of an hour will have passed, leaving almost exactly 2 hours on the e rope. Immediately light the other end of the e rope, and the remaining rope will burn out in almost exactly an hour. In fact, if you can time it perfectly, you will be able to time an interval of 1 hour, 0 minutes, and 20.1 seconds between the moment you light the second end of the e rope and the moment the e rope burns out.

This all works because, even though the ropes burn irregularly, if you light both ends at the same time, the two flames will meet in exactly half the burn time of the entire rope.