## Saturday, August 1, 2009

### It's all in the Speedo LZR suit...

Speedo LZR swimsuits could apparently make you swim 1% faster. A proof to it is an avalanche of broken world records at the 2009 FINA world swim championship in Rome. Worrying that swimming becomes a matter of clothes rather than sportsmanship, world swimming council decided to ban this "magical" suit from the future competitions. Now, that suits will be banned, they may be coming on sale...
Who wouldn't look good in this elegant black and gray super skin?

If you swim with half of Michael Phelp's speed, how many suits do you need to put on, in order to reach his speed?

Submit your answer on our Family Puzzle Marathon site. Solve three puzzles and get a prize!

Maria said...

I know, she looks so good in the suit that everyone is intimidated to "try the puzzle on"...
It is a bit more complex than some other, so let me start the ball:
If S is your speed, every time you put a suit on it becomes 101/100 x S.
Second suit gets you to a speed of 101/100 x 101/ 100 x S.
Can you continue rolling?

Alin Grin said...

1.01^x=2
1,01^x=1.01^70
x=70

70 LZR suits will double your speed if each suit you wear on top of the previous one increases your speed by %1.

Maria said...

That's right!
Let me just explain how Alin got to his answer to us, mere mortals:
As I wrote above, every suit improves your speed by 1%, making it 101/100 times your speed.
So, first suit will make your speed: 1.01 x S
second: 1.01^2 x S
etc
suit number X will make your speed 1.01^X x S
We want this speed to be 2 x S, as we know that Michael Phelp's speed is twice than your speed, S.

1.01^X x S = 2 x S
1.01^X = 2

the easiest way to solve this is by substituting some numbers.
if X=50, 1.01^50 = 1.64 too small
if X=100, 1.01^100 = 2.7 too big
X=70 works: 1.01^70 = 2.006