Number of trials, n = 15 Expected success, r = 13 Probability of having a VCR, p = 70% = 0.7 Probability of not having a VCR, q = 1 - p = 0.3
According to the binomial distribution, the probability of 13 out of 15 households having a VCR is ₁₅C₁₃ p¹³ q¹⁵⁻¹³ = [15!/(13!2!)]*(0.7¹³)*(0.3²) = 0.0916