In a group of 100 children, the mean weight of children is 15 kg. The standard detion is 1.5 kg. Which one of the following is true?: (A) 95% of all children weight between 12 and 18 kg, (B) 95% of all children weight between 13.5 and 16.5 kg, (C) 99% of all children weight between 12 and 18 kg, (D) 99% of all children weight between 13.5 and 16.5 kg
Answer is A. In the given question, n = 100 children, Mean weight (u) = 15 kg, SD = 1.5 kg, 95% of value are contained in Mean + 2SD (u+ 2s), Thus 95% of all children will have weight between 15 + 2 (1.5) i.e. between 12 and 18 kg.