9march

Magic Belt Problem Solution

A magic wish-granting rectangular belt always shrinks to 1/2 its length and 1/3 its width whenever its owner makes a wish. After three wishes, the surface area of the belt's front side was 4 cm2.
What was the original length, if the original width was 9 cm?


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Solution:



Let the original lenght = x cm.
and the given width = 9 cm.
1st wish:
lenght =x/2 cm; width =9/3=3 cm;
2nd wish:
lenght =x/4 cm; width =1 cm;
3rd wish:
lenght =x/8 cm; width =1/3 cm;

After three wishes:

The given Surface area A (say) = 4 cm2;
Surface area A = length * width;

4 cm2 =(x/8 )*(1/3) cm2;
x = 4 *24= 96 cm;
The original length x= 96 cm;