Finding the Fourth Proportional to 99.91, 137.88 and 56.25

Step by Step Solution

1. Step 1: Write the proportion equation
   99.91 : 137.88 = 56.25 : x
2. Step 2: Convert to fraction form
   99.91/137.88 = 56.25/x
3. Step 3: Cross multiply
   99.91x = 137.88 × 56.25
4. Step 4: Simplify right side
   99.91x = 7,755.91
5. Step 5: Solve for x
   x = 7,755.91/99.91
6. Step 6: Final answer
   x = 77.63