Finding the Fourth Proportional to 1,077.34, 1,615.59 and 428.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,077.34 : 1,615.59 = 428.50 : x
2. Step 2: Convert to fraction form
   1,077.34/1,615.59 = 428.50/x
3. Step 3: Cross multiply
   1,077.34x = 1,615.59 × 428.50
4. Step 4: Simplify right side
   1,077.34x = 692,280.32
5. Step 5: Solve for x
   x = 692,280.32/1,077.34
6. Step 6: Final answer
   x = 642.58