Question

A 1:20,000,000 scale map of the united states displays the interstates with a line symbol that is 3.4 points wide. there are 72 points to an inch. what is the uncertainty in the location of the road due to the width of the line used to represent it

Answer 1

Scale map ------------ > 1/20000000

if 72 points-----------------------------------> 1 in
3.4 points (line wide)----------------------- > X
X=3.4/72=0.0472222 in

therefore
1 ------------------------------------ > 20000000
0.0472222------------------------- > x
x=0.0472222*20000000=944444 in-------------- >944.44*2.54/100=23989 m

1feet------ > 0.30 m
x-------------> 23989
x=23989/0.3=79963 ft

the answer is
The uncertainty in the location of the road is about 23989 m/ 79963 ft