Finding the Fourth Proportional to 1,428.72, 1,972.58 and 897.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.72 : 1,972.58 = 897.80 : x
2. Step 2: Convert to fraction form
   1,428.72/1,972.58 = 897.80/x
3. Step 3: Cross multiply
   1,428.72x = 1,972.58 × 897.80
4. Step 4: Simplify right side
   1,428.72x = 1,770,982.32
5. Step 5: Solve for x
   x = 1,770,982.32/1,428.72
6. Step 6: Final answer
   x = 1,239.56