Finding the Fourth Proportional to 1,045.89, 1,567.50 and 428.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,045.89 : 1,567.50 = 428.88 : x
2. Step 2: Convert to fraction form
   1,045.89/1,567.50 = 428.88/x
3. Step 3: Cross multiply
   1,045.89x = 1,567.50 × 428.88
4. Step 4: Simplify right side
   1,045.89x = 672,269.40
5. Step 5: Solve for x
   x = 672,269.40/1,045.89
6. Step 6: Final answer
   x = 642.77