Finding the Fourth Proportional to 100.41, 138.72 and 99.77

Step by Step Solution

1. Step 1: Write the proportion equation
   100.41 : 138.72 = 99.77 : x
2. Step 2: Convert to fraction form
   100.41/138.72 = 99.77/x
3. Step 3: Cross multiply
   100.41x = 138.72 × 99.77
4. Step 4: Simplify right side
   100.41x = 13,839.40
5. Step 5: Solve for x
   x = 13,839.40/100.41
6. Step 6: Final answer
   x = 137.83