City X has a population 5 times as great as the population of City Y, which has a population twice as great as the population of City Z. What is the ratio of the population of City X to the population of City Z?	Select:
A) 1:8 B) 1:4 C) 2:1 D) 4:1 E) 10:1
x= 5y, y= 2*z   X : Y , Y : Z   5 : 1 , 2 : 1   10 : 2 , 2 : 1   So, X : Z = 10 : 1   (10:1)
<result>E</result>
City X has a population 5 times as great as the population of City Y, which has a population twice as great as the population of City Z. What is the ratio of the population of City X to the population of City Z?