The true statement about characteristics of a representative sample are:
The essential characteristics of a representative sample are:

Its size should be 30 or more–the larger the sample, lesser would be the error due to chance.
It should randomly be selected by an appropriate sampling technique so that each member of the population has an equal opportunity of being selected.

The rules for selection should be independent of the observation to be made. If the sample represents the population, its values or statistics like Mean, SD(s) or proportion (p) will not differ significantly from population parameters or true value μ, σ or P, respectively. Difference found will not exceed the chance error. If you pick up an apple of any size from a heap, it does not represent the entire lot. It may be of big, small or medium size. Its size and weight may not be equal to the mean size and weight of the lot. If you pick up 30 at random after mixing all sizes, you will get a representative sample of 30 apples representing the entire heap (sufficiently large and unbiased). The seller can then fix the rate of 30 apples from any side of the heap, not allowing the customer to choose.
Its size should be 30 or more–larger the sample, lesser would be the error due to chance.
It should randomly be selected by an appropriate sampling technique so that each member of the population has an equal opportunity of being selected.
Both
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