**12. Incorrect. The answer is true, not false**

Observed frequencies of tails are
x_{1}=116 and x_{2}=84.

Expected frequencies if the coin
is fair are np_{1}=100 and np_{2}=100. Then

χ^{2}=(x_{1}-np_{1})^{2}/np_{1}
+ (x_{2}-np_{2})^{2}/np=(116-100)^{2}/100 +
(84-100)^{2}/100 = 2.56+2.56=5.12.

The critical value c^{2}_{0.95}
for 1 degrees of freedom (n=k-1=2-1) is 3.84, we fail to reject the hypothesis that
the coin is fair at 5% significance level.