Answer to Question #297900 in Statistics and Probability for clemclem

Question

Monthly food expenditures for families in Caloocan City average Php 4 500 with a standard deviation of Php 750. Assuming that the monthly food expenditures are normally distributed, what percentages of the expenditures are between Php 3 900 and Php 5 850?

Answer 1

$P(3900<X<5850)=P(\frac{3900-4500}{750}<Z<\frac{5850-4500}{750})=$

$P(-0.8<z<1.8)=P(Z<1.8)-P(Z<-0.8)=0.5722=75.22\%.$