The length of a part in a drawing made at a scale of 1: 3 is 2.4 cm.

The length of a part in a drawing made at a scale of 1: 3 is 2.4 cm. What will be the length of this part in another drawing made at a scale of 2: 1?

Method 1: We use the rule of finding a number by its fraction. If 1 \ 3 (i.e. 1: 3) = 2.4. to find a number by its fraction, the value of the fraction must be multiplied by the denominator and divided by the numerator: 2.4 * 3: 1 = 7.2. This is the actual size of the part. Now we will find the size of the part at a scale of 2: 1. for this 7.2 * 2: 1 = 14.4.
Method 2: use the proportion property:
1 \ 3 = 2.4
2 \ 1 = x,
by the property of proportion we have: 1 \ 3 * x = 2 \ 1 * 2.4. Expressing x, we get: x = 2.4 * 2 * 3 = 14.4
Answer: 14.4