Finding the Fourth Proportional to 1,111.53, 1,533.86 and 639.45

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.53 : 1,533.86 = 639.45 : x
2. Step 2: Convert to fraction form
   1,111.53/1,533.86 = 639.45/x
3. Step 3: Cross multiply
   1,111.53x = 1,533.86 × 639.45
4. Step 4: Simplify right side
   1,111.53x = 980,823.58
5. Step 5: Solve for x
   x = 980,823.58/1,111.53
6. Step 6: Final answer
   x = 882.41