What is documentary source
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Documentary sources may be defined loosely as records relating to individuals or groups of individuals that have been generated in the course of their daily lives.

the effect of the ming leaders banning ships with more than two masts was that there was no further construction of ships masts, because there was a surplus. ming emperors disallowed foreign exploration

part a. there were 250 teenagers surveyed (100% of tenagers = 250)therefore 1 % = 250/100 = 2.5 76% = 1% x 76 = 2.5 x 76 = 190 teenagers of the 250 surveyed liked burgerspart b: jane surveyed 25% (which is equal to 50 teenagers, i.e. a quarter of the teenagers surveyed is 50) to get 100% we simply get 4 quarters, i.e. multiply 50 by 4 = 200 teenagers were surveyed by jane. part c: it is impossible to give an example where a percentage is greater than 100%, since, by definition , percentage means "per 100".