(b) \(\frac{13}{50}\)
Probability (contradiction) = P(A speaks truth) × P(B does not speak truth) + P(A does not speak truth) × P(B speaks truth)
= \(\frac{80}{100}\times\frac{10}{100}\) + \(\frac{20}{100}\times \frac{90}{100}\)
= \(\frac{8}{100}\)+ \(\frac{18}{100}\) = \(\frac{26}{100}\) = \(\frac{13}{50}\)