Scale Flashcards

All 7 cards in this deck

On a map, what does a scale of $1:25\,000$ mean?

1 unit on the map represents $25\,000$ of the same unit in real life.

How do you convert a map length into a real distance?

e.g. 8 cm on a map with scale 1 cm to 4 km

Multiply the map length by the scale.
$8 \times 4 = 32$ km

How do you find the length to draw on a map for a given real distance?

e.g. real length 10 km, scale 1 cm to 4 km

Divide the real distance by the scale.
$10 \div 4 = 2.5$ cm

To change a real distance in cm into km, what do you divide by?

$100\,000$.
e.g. $350\,000$ cm $\div\ 100\,000 = 3.5$ km

True or false? A scale of $1:1200$ means 1 cm on the drawing represents 1200 cm in real life.

True. $1200$ cm is 12 m, so 1 cm represents 12 m.

What are the steps to estimate a real height from a picture using a known reference length?

e.g. a bus of real length 12 m measures 2 cm; the building measures 5 cm

1. Measure both the reference object and the unknown object on the picture: 2 cm and 5 cm
2. Find the scale factor between them: $5 \div 2 = 2.5$
3. Multiply the known real length by it: $12 \times 2.5 = 30$ m

What are the steps to make a scale drawing of a rectangle?

e.g. a 35 m by 20 m rectangle, scale 1 cm to 5 m

1. Divide each real length by the scale: $35 \div 5 = 7$, $20 \div 5 = 4$
2. Draw accurately with a ruler: a 7 cm by 4 cm rectangle
3. Measure the drawing and convert back to find any real measurement