Finding the Fourth Proportional to 99.97, 137.70 and 78.10

Step by Step Solution

1. Step 1: Write the proportion equation
   99.97 : 137.70 = 78.10 : x
2. Step 2: Convert to fraction form
   99.97/137.70 = 78.10/x
3. Step 3: Cross multiply
   99.97x = 137.70 × 78.10
4. Step 4: Simplify right side
   99.97x = 10,754.03
5. Step 5: Solve for x
   x = 10,754.03/99.97
6. Step 6: Final answer
   x = 107.58