The standard error of the distribution of sample proportions is 0.084
The correct option is (B).
What is standard error?
Standard error is calculated by dividing the standard deviation of the sample by the square root of the sample size.
Given: Â population parameter: 0.7, n=30
Standard error:  √[p (1 - p) / n]
= √[0.7 (1 - 0.7) / 30]
=  √[0.7*0.3 / 30]
=  √0.21 / 30
= √0.007
=0.0836
=0.084
Hence, the standard error is 0.084.
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