Finding the Fourth Proportional to 99.72, 149.76 and 78.12

Step by Step Solution

1. Step 1: Write the proportion equation
   99.72 : 149.76 = 78.12 : x
2. Step 2: Convert to fraction form
   99.72/149.76 = 78.12/x
3. Step 3: Cross multiply
   99.72x = 149.76 × 78.12
4. Step 4: Simplify right side
   99.72x = 11,699.25
5. Step 5: Solve for x
   x = 11,699.25/99.72
6. Step 6: Final answer
   x = 117.32