Finding the Fourth Proportional to 100.37, 138.35 and 78.50

Step by Step Solution

1. Step 1: Write the proportion equation
   100.37 : 138.35 = 78.50 : x
2. Step 2: Convert to fraction form
   100.37/138.35 = 78.50/x
3. Step 3: Cross multiply
   100.37x = 138.35 × 78.50
4. Step 4: Simplify right side
   100.37x = 10,859.98
5. Step 5: Solve for x
   x = 10,859.98/100.37
6. Step 6: Final answer
   x = 108.20