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Shinji_Hirako

Joe gave Bill a magic wishing carpet measuring 1m by 2m. each time bill sat on it and made a wish, he recieved his wish, but the length of the carpet decreased by 1/2 and the width decreased by 1/3

i) express the area of the carpet A as an exponential function of the number of wishes n, simpfy the expresion so it contains only one power

ii) when area of carpet decrease to less than 200cm square, bill cant sit on it, and cant grant anymore wishes, how many wishes will he recieve

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Hatashi

I suck at math.

I am curious for the answer though.

Shinji_Hirako

I hate math, thank god I don't need to take math next year.

this question makes no sense to me :'(

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Hatashi

Well...
Surface = 1 x 2 = 200cm²

1/2 = half...

Aaaah **** this, never really solved math problems in English, so I don't really know what to do next.

Peakevo

Dunno.Hate Math myself.

In other news.Nasty Nas in yuh area,about to cause mass hysteria.

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Shinji_Hirako

Anyone know how to solve this question?

i'm sooo screwed.

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Alivada

Bill should wish that the carpet could never decrease insize.

Nogardreyals

soo easy , im not sure if im right though

i) number of wishes is n.
area = l * w = 1 * 2 = 2m squared.

Lets say he sat on it once, the length would go down 1/2 and width would go down 1/3.

so for 1 wish: l * w = 1 * 1/2 * 2 * 1/3
for 2 wish: l * w = 1 * 1/2 * 1/2 * 2 * 1/3 * 1/3 = 1*(1/2)^2 * 2*(1/3)^2

for 3 wish: l * w = 1*(1/2)^3 * 2*(1/3)^3
...recognize the pattern

area ( in meters squared) = l * w
= (initial length * 1/2 ^ number of wishes) * (initial width * 1/3 ^ number of wishes)
= (1/2)^ n * 2 (1/3)^ n

ii) 200cm squared = 0.02 m squared

so find when area = 200cm
so let what we found
n = number of wishes
(1/2)^ n * 2 (1/3)^ n = 0.02 meters squared (because 200cm squared = 0.02 m squared)
= 2.57
= 3


3 wishes

man the trick is 100cm squared is not equal to 1m squared.
and remember what unit ur formula makes

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Wahoo

not quite, for 1. you need to express it with a single power. You are also taking the wrong multiple, you need to multiply by 2/3, not 1/3, since that is what is remaining once you remove the 1/3 of carpet. Since you show in the workings that you're just multiplying 1/2's and 2/3's exponentially by n, just use them in a single power, like so: 1 * 2 * (1/2 * 2/3) ^ n, or, 2 * 1/3^n m sq.

for 2.) the carpet is 2m sq = 20000 cm sq, so just change the 2 in the formula to 20000 and work from there till you get an answer < 200. I think it's 5.

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