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Water makes up 96% of the weight of a cucumber. When cucumber is left out in the sun, some water evaporates,
and water then makes up 95% of the weight of the sun dried cucumber.
What percentage of its original weight does the cucumber lose when the water evaporates?
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Let assume that the initial weight (mass) was 100 kg of cucumbers. (It is better to say "mass").
It means that the content of water initially was 96 kilograms. Respectively, the mass of the solid part ("the fiber") was 4 kilograms.
After drying, when the water partly went out, we have the same mass of the fiber of 4 kg, and some new mass of remaining water,
let say w kilograms. According to the condition, the equation for w after drying is
= 0.95.
Let us solve it. For it, multiply both sides by (4+w). You will get
w = 4*0.95 + 0.95w, or
w*(1-0.95) = 4*0.95, or
0.05*w = 4*0.95.
Hence, w = = 4*19 = 76 kg.
OK, very good. Then new mass of the cucumbers after drying is 76 + 4 = 80 kilograms.
Thus the vegetable does lose 20% of its initial mass: indeed, = 20%.
It is unexpected result. But this is well known fact.