Finding the Fourth Proportional to 1,187.50, 1,638.76 and 663.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,187.50 : 1,638.76 = 663.56 : x
2. Step 2: Convert to fraction form
   1,187.50/1,638.76 = 663.56/x
3. Step 3: Cross multiply
   1,187.50x = 1,638.76 × 663.56
4. Step 4: Simplify right side
   1,187.50x = 1,087,415.59
5. Step 5: Solve for x
   x = 1,087,415.59/1,187.50
6. Step 6: Final answer
   x = 915.72