Finding the Fourth Proportional to 100.53, 138.72 and 59.05

Step by Step Solution

1. Step 1: Write the proportion equation
   100.53 : 138.72 = 59.05 : x
2. Step 2: Convert to fraction form
   100.53/138.72 = 59.05/x
3. Step 3: Cross multiply
   100.53x = 138.72 × 59.05
4. Step 4: Simplify right side
   100.53x = 8,191.42
5. Step 5: Solve for x
   x = 8,191.42/100.53
6. Step 6: Final answer
   x = 81.48