Brain Teasers
Clean Those Windows!
A girl has been assigned to window cleaning for the day. She has to clean three windows, all different sizes. However, the girl is very pale and burns easily, so she wants to decide which SPF factor to use. She begins cleaning at 12:00 in the morning and can clean 1 square metre in 1 minute. The first window is 10' by 10', the second 9' by 16', and the third 9' by 20'. Assuming that any SPF sunscreen is available, which one should she buy?
Answer
0. She starts at 12:00 in the morning, or midnight. At that time, the sun isn't up yet.Hide Answer Show Answer
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Comments
Hmmm...I guess 12 in the morning is the same as 12 at night. I hadn't really thought of this before. Thanks for the teaser!
Why would anyone clean windows at 12 AM? How could you see well enough to know if you'd gotten all the streaks off?
Also,you didn't mention whether she was cleaning the insides or outsides or both - makes a difference!
Also,you didn't mention whether she was cleaning the insides or outsides or both - makes a difference!
The trick category kind of gave it away
1) some people call noon - 12 in the morning.
2) 'she cleans 1 METER per minute', the first window is 10 FEET by 10 FEET, there is a measurement error.
3) 'assuming any SPF is available', just use the strongest one you can find. It didn't explain why you would need to figure out the number, or how to figure it out.
2) 'she cleans 1 METER per minute', the first window is 10 FEET by 10 FEET, there is a measurement error.
3) 'assuming any SPF is available', just use the strongest one you can find. It didn't explain why you would need to figure out the number, or how to figure it out.
Eh...not the best one Ive seen, good try though, keep trying
Assuming any sunscreen was available, she should get the one with the highest SPF, but I totally didn't pick up on the midnight thing.
Nicky and WC -
"SPF" stands for "Sun Protection Factor." The number refers to the number of hours that particular lotion is supposed to sheild the user from the sun's harmful rays.
The "trick" was that you were supposed to waste a lot of time, brainpower, and pencil lead converting square meters to square feet, then figuring out how many hours the poor girl would be out in the blistering sun - hey - what if she were cleaning the windows in Norway or Alaska, out there sweltering in the Midnight Sun???? Let's see... a meter is a little over three feet...
"SPF" stands for "Sun Protection Factor." The number refers to the number of hours that particular lotion is supposed to sheild the user from the sun's harmful rays.
The "trick" was that you were supposed to waste a lot of time, brainpower, and pencil lead converting square meters to square feet, then figuring out how many hours the poor girl would be out in the blistering sun - hey - what if she were cleaning the windows in Norway or Alaska, out there sweltering in the Midnight Sun???? Let's see... a meter is a little over three feet...
You got it unklemyke!
good teaser had to think that for a second
yay! I was about to get a calculator out just to be sure that she could get all the windows done within at least six hours but in the end I said nah she has plenty of time till the suns up! I liked it not too hard but neat.
You got me
Was wondering if some sort of opaque windows would be in order but then realised that would be more her cleaning a wall.
Was wondering if some sort of opaque windows would be in order but then realised that would be more her cleaning a wall.
pretty good. Interesting piece of info about the SPF definition - thanks!
You realize that they don't sell 0 SPF sunscreen, and even if they did, there would be no point in buying it, right?
If she was cleaning windows in Australia at 120 a.m. EST (Eastern Standard Time, in the western Hemisphere), then it would be bright.
If she was cleaning windows in Australia at 120 a.m. EST (Eastern Standard Time, in the western Hemisphere), then it would be bright.
I knew it. >_>
Kinda obtuse, but cool.
OH! I got it!!
It got me.
well wccope, although some people call noon 12 in the morning they are incorrect that is the point of this TRICK teaser
If she worked in the arctic during the summer, the sun is up at 12 : 00 in the morning...
Haha, good teaser.
Haha, good teaser.
Lol, great teaser! I thought she would just buy the highest SPF sunscreen.
AAAAARRRGGGGHH!!!!!!!
What if she was in Alaska (or somewhere similar)?
Midnight Sun (from Wikipedia)-
The midnight sun is a natural phenomenon occurring in summer months at latitudes north and nearby to the north of the Arctic Circle, and south and nearby to the south of the Antarctic Circle where the sun remains visible at the local midnight.
Midnight Sun (from Wikipedia)-
The midnight sun is a natural phenomenon occurring in summer months at latitudes north and nearby to the north of the Arctic Circle, and south and nearby to the south of the Antarctic Circle where the sun remains visible at the local midnight.
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