From past experience, it is known 90% of one-year-old children can distinguish their mother's voice from the voice of a similar sounding female. A random sample of 20 one-year-olds is given this voice recognition test. Find the probability at least 3 children do not recognize their mother's voice.
+1223 subtract the probability that 0, 1, or 2 children don't recognize their mother's voice from 1
1−(0.9)20−(0.1)1(0.9)19−(0.1)2(0.9)18≈0.8634
