Finding the Fourth Proportional to 100.76, 139.06 and 61.42

Step by Step Solution

1. Step 1: Write the proportion equation
   100.76 : 139.06 = 61.42 : x
2. Step 2: Convert to fraction form
   100.76/139.06 = 61.42/x
3. Step 3: Cross multiply
   100.76x = 139.06 × 61.42
4. Step 4: Simplify right side
   100.76x = 8,541.07
5. Step 5: Solve for x
   x = 8,541.07/100.76
6. Step 6: Final answer
   x = 84.77