SME
Grade 7 Math · Problem type
Map distances in miles
Use this for “On a map, 1 inch represents 25 miles. Two towns are 3.5 inches apart. How far apart are they?”
Diagram
d = 3.5 in on the top line sits over 87.5 mi on the bottom line: each 1 above is 25 below.
This is an example. Type your own values to start a new problem.
a (mi)
=
s
×
d (in)
Formulas
a
=
s
×
d
(actual
distance
=
miles
for
1
inch
on
the
map
×
distance
on
the
map)
87.5 = 25 × 3.5
Assumptions
•
A map scale says what 1 in on the map stands for: 1 in represents 25 mi.
•
Every distance on the map is multiplied by the same number.
•
Measure the map distance, then multiply by the miles for each inch.
Step-by-step
WE KNOW
s = 25 (miles for 1 inch on the map), d = 3.5 in (distance on the map)
FIND
actual distance (a)
Step 1 · Find actual distance (a)
Use a = s × d (actual distance = miles for 1 inch on the map × distance on the map)
Each
inch
on
the
map
stands
for
s
miles.
a
=
25
×
3.5
a
=
87.5
mi
Check
Put the numbers back in. Both sides should match.
87.5 = 25 × 3.5 ✓
Topic check
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