----------------------------------------------- Define x ----------------------------------------------- Let Alice be x years old 3 years ago.
----------------------------------------------- Age as at 3 years ago : ----------------------------------------------- Alice = x years Jane = 3x
----------------------------------------------- Present age : ----------------------------------------------- Alice = x + 3 Jane = 3x + 3
----------------------------------------------- Age in two years time : ----------------------------------------------- Alice = x + 3 + 2 = x + 5 Jane = 3x + 3 + 2 = 3x + 5
----------------------------------------------- Construct equation : ----------------------------------------------- In two years time, the sum of their age will be 62: x + 5 + 3x + 5 = 62 4x + 10 = 62 4x = 62 - 10 4x = 52 x = 13
----------------------------------------------- Find their present age : ----------------------------------------------- Alice = x + 3 = 13 + 3 = 16 years old Jane = 3x + 3 = 13(3) + 3 = 42 years old
---------------------------------------------------------------------------------------------- Answer: Alice is 16 years old and Jane is 42 years old. ----------------------------------------------------------------------------------------------
Randomly assigned group. the art class isn't random and only consists of a select type of people--it is not a representative sample; maybe more left handed people enjoy art than do right handed people! therefore, even though the randomly assigned group is smaller, it is the better estimate.