Finding the Fourth Proportional to 100.51, 138.69 and 56.83

Step by Step Solution

1. Step 1: Write the proportion equation
   100.51 : 138.69 = 56.83 : x
2. Step 2: Convert to fraction form
   100.51/138.69 = 56.83/x
3. Step 3: Cross multiply
   100.51x = 138.69 × 56.83
4. Step 4: Simplify right side
   100.51x = 7,881.75
5. Step 5: Solve for x
   x = 7,881.75/100.51
6. Step 6: Final answer
   x = 78.42