Hello, here is a question for Probability and Statistics. Please show the solution with full explanation. Thank you

4. From past experience, it is koovvn 9% of one-year-old children can distinguish their mother's voice from the voice of a similar sounding female. A random sample of 2!] one-year-olds is given this voice recognition test. {Round your answers to three deciinal places if necessary} a} Find the probability at least 3 children do not recognize their mother's voice. b) Find the probability all 2t} children recognize their mother's voice. e) Let the random variable 1: denote the number of children who do not recognize their mother's voice. Find the variance of r. d) Find the probability that at most 4 children do not recognize their mother's voice