A scale on a map is 1 1/2 inches = 10 miles. How many miles does a 21 inch line represent?

Question

calculusxy · Answer

Here are the options:
a. 31 1/2
b. 140
c. 0.714
d. 150
e. none of the above

*I chose A. 31 1/2.

anonymous · Answer

11/2  for 10 miles 
21 for  10/(11/2)*21=420/11 miles

calculusxy · Answer

i meant one and a half not eleven over two

anonymous · Answer

oh..then 10/(3/2)*21=70

calculusxy · Answer

ok so i here is another question:

A 10-minute call to Hawaii after 9 p.m. costs $5.75. if the charges for the first 3 minutes was $3.65, what was the charge for each additional minute?

directrix · Answer

A scale on a map is 1 1/2 inches = 10 miles. How many miles does a 21 inch line represent?

(3/2)/10 = 21/x which means 1.5 inches is to 10 miles as 21 inches is to x miles.

(3/2)/10 = 21/x 

@apurvasijaria   I cranked this out and did not get 70 as you reported above
 >> oh..then 10/(3/2)*21=70

Would you show me the error in my work? Thanks.

directrix · Answer

@calculusxy

>>> *I chose A. 31 1/2.    Not correct

anonymous · Answer

@Directrix  I cranked this out and did not get 70 as you reported above
sorry my mistake its 140.

directrix · Answer

@apurvasijaria   Thanks for checking.