Calculating the Actual Length of a Railway Line from a Map Scale

To find the actual length of the railway line, we can use the scale provided on the map.

1. The scale of 1 : 200,000 means that 1 cm on the map represents 200,000 cm in reality.
2. If the railway line measures 3.5 cm on the map, we can calculate the real length as follows:

[ text{Actual length} = text{Map length} times text{Scale factor} ]

[ text{Actual length} = 3.5 , text{cm} times 200,000 , text{cm} ]

3. Calculating that gives:

[ text{Actual length} = 700,000 , text{cm} ]

4. Now, to convert centimeters to kilometers, we divide by 100,000 (since there are 100,000 cm in 1 km):

[ 700,000 , text{cm} div 100,000 = 7 , text{km} ]

Therefore, the actual length of the railway line is 7 km.

The correct answer is 1. 7 km.