160 heads and 240 tails resulted from 400 tosses of a coin. Find a 95% confidence interval for the probability of a head. Does this appear to be a fair coin?
[Hint p = $$\frac{1}{2}$$, q = $$\frac{1}{2}$$, n = 400
Expected frequency = np = 200
Standard error = $$\sqrt {npq} $$ = 10
Actual difference = 200 - 160 = 40
Difference is greater than 3 times standard error coin is unfair.]

A. Can be said to be fair

B. Can be or cannot be said to be fair

C. Cannot be said to be fair

D. None of the above

Answer: Option C