Finding the Fourth Proportional to 1,219.76, 1,830.18 and 642.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,219.76 : 1,830.18 = 642.50 : x
2. Step 2: Convert to fraction form
   1,219.76/1,830.18 = 642.50/x
3. Step 3: Cross multiply
   1,219.76x = 1,830.18 × 642.50
4. Step 4: Simplify right side
   1,219.76x = 1,175,890.65
5. Step 5: Solve for x
   x = 1,175,890.65/1,219.76
6. Step 6: Final answer
   x = 964.03