Half My Life

[Keith&Co.]

Not a terribly complicated puzzle, but one that seems to antagonize the living shit out of my kids when i told them. And some of my students. And some of my wife's students.

I spent half my life in the Navy, twice.

There was one enlistment in 1980.
One retirement in 2000.
A total of 20 years in uniform (20 years, 3 mos and 3 days, to be ultra accurate, but not important here).

I joined when i was 17. At 34, i'd spent half my life in the Navy. I retired when i was 37. Three years after i was out, i was 40, and once more, i had spent half my life in the Navy. it's pretty straightforward.

But MAN! Make that statement in front of reasonably intelligent high school students, and they lose their minds trying to 'figure it out.'

They've suggested that the answer means i died on the operating table at some point, or an assumed identity is involved, or i got out and got back in again, or i have multiple personality disorder...
It's fun! A LEETLE disappointing when i explain it. But fun.

 

[Tom Sawyer]

So what, you joined the Navy for six month intervals every year since you were born or something? Your statement makes no sense.

 

[Keith&Co.]

Yeah, like that.

 

[Daisy]

So what, you joined the Navy for six month intervals every year since you were born or something? Your statement makes no sense.

Are you kidding?

 

[Tom Sawyer]

So what, you joined the Navy for six month intervals every year since you were born or something? Your statement makes no sense.

Are you kidding?

No. Navy regulations forbid them from enlisting babies, even for only a few months. If that was what he was saying then his statement made no sense.

 

[Jimmy Higgins]

So what, you joined the Navy for six month intervals every year since you were born or something? Your statement makes no sense.

Are you kidding?

No. Navy regulations forbid them from enlisting babies, even for only a few months. If that was what he was saying then his statement made no sense.

At age 34, he spent half his life in the Navy, but he wasn't done.

In order for the second claim to be true, half of his life in the Navy at 40, then he would have had to of worked half of the years between being 34 and 40. He worked until he was 37 (17 + 20), which is three years, half of his years between 34 and 40.

Yeah, I rock remedial arithmetic!

 

[blastula]

I get it. You're Jesus.

 

[Keith&Co.]

I get it. You're Jesus.

My Jesus?
Jesus isn't mine!
I never welcomed that judgmental jerk into my heart.
Don't give me any 'your Jesus' crap.

 

[4321lynx]

So what, you joined the Navy for six month intervals every year since you were born or something? Your statement makes no sense.

Are you kidding?

No. Navy regulations forbid them from enlisting babies, even for only a few months. If that was what he was saying then his statement made no sense.

At age 34, he spent half his life in the Navy, but he wasn't done.

In order for the second claim to be true, half of his life in the Navy at 40, then he would have had to of worked half of the years between being 34 and 40. He worked until he was 37 (17 + 20), which is three years, half of his years between 34 and 40.

Yeah, I rock remedial arithmetic!

Yeah, but what a way to get there.

!. At 34 he had spent 17 years in the Navy , therefore half his life.
2. At 37, after 20 years in Navy he retired.
3. At his 40th birthday he "again" had spent half his life (twenty of those 40 years) in the Navy
4. Only gets one pension, for 20 years' service, not for 1/2 + 1/2 = a whole lifetime of it.

 

[Dutch_labrat]

Easy, also why thinking in curves helps with maths.

Imagine (or draw) a curve where the Y is % percentage of life spend in the navy and X is the age.

The curve starts at 0 and remains there until enlistment where it starts to rise. Somewhere it crosses the 50% line but continues to rise because he was still floating around.

Once out of the navy the curve dips downward and after a while hits the 50% again.

When in doubt DRAW!

 

[fast]

So what, you joined the Navy for six month intervals every year since you were born or something? Your statement makes no sense.

Are you kidding?

No. Navy regulations forbid them from enlisting babies, even for only a few months. If that was what he was saying then his statement made no sense.

At age 34, he spent half his life in the Navy, but he wasn't done.

In order for the second claim to be true, half of his life in the Navy at 40, then he would have had to of worked half of the years between being 34 and 40. He worked until he was 37 (17 + 20), which is three years, half of his years between 34 and 40.

Yeah, I rock remedial arithmetic!

Yeah, but what a way to get there.

!. At 34 he had spent 17 years in the Navy , therefore half his life.
2. At 37, after 20 years in Navy he retired.
3. At his 40th birthday he "again" had spent half his life (twenty of those 40 years) in the Navy
4. Only gets one pension, for 20 years' service, not for 1/2 + 1/2 = a whole lifetime of it.

Yes, that's what I came up with. At the age of 17, he joined the group, and 17 years later, he was 34 years old, so if someone at the time would have remarked that he had spent 1/2 his life in the Navy, he would have been correct (34 / 2) ... 17

On his 40th birthday, he was asked, how many years did you spend in the Navy. He said, "well, let's see here, I enlisted when I was 17 and got out when I was 37, so I spent 20 years in the Navy--at which someone promptly noted that he had spent half his life in the Navy (40 / 2) ... 20

The problem is that it is not therefore true that he had spent half his life in the Navy twice ... Hence, he did not spend both 17 and 20 years in the Navy. You can't count each year he spent in the Navy more than once.

 

[Random Person]

I get it. You're Jesus.

My Jesus?
Jesus isn't mine!
I never welcomed that judgmental jerk into my heart.
Don't give me any 'your Jesus' crap.

You may be a math magician but you're not very good at reading comprehension.


Say this is fun. Now you see how your kids feel.

 

[Unbeatable]

Reminds me of this Mitch Hedberg joke: "I used to do drugs. I still do. But I used to, too."

 

[fast]

Reminds me of this Mitch Hedberg joke: "I used to do drugs. I still do. But I used to, too."

And that reminds me of the "suggestion"/"implication" distinction. That he says he used to highly suggests that he longer does, but because the mere fact he used to doesn't entail that he longer does, there's still room for the possible fact he still does.

 

[Speakpigeon]

I spent half my life in the Navy, twice.

Since you're teaching kids maybe you'd be interested by the following suggestion: Shouldn't you have said: "I had spent half my life in the Navy, twice."?
Me I think so. You?
EB

 

[James Brown]

Reminds me of this Mitch Hedberg joke: "I used to do drugs. I still do. But I used to, too."

Or the old trick to get into a bar:

"How old are you?"

"I'm going to be 22."

"When"

"Uh . . . in four-and-a-half years?"