a psychologist claims that the mean age at which children start walking is 12.5 months with a standard deviation of 0.80 month. carol wanted to check...

a psychologist claims that the mean age at which children start walking is 12.5 months with a standard deviation of 0.80 month. carol wanted to check if this claim is true. she took a random of 18 children and found that the mean age at which these child