Question

the weights of 1000 children have average of 45 kilograms and a standard deviation of 5 kilograms, how many children weight 35 kg to 55 kg

Answer 1

$P(35<X<55)=P(\frac{35-45}{5}<Z<\frac{55-45}{5})=P(-2<Z<2)=$

$=P(Z<2)-P(Z<-2)=0.9545.$

Number of children: $n=1000*0.9545=955.$