Finding the Fourth Proportional to 156.01, 215.41 and 100.78

Step by Step Solution

1. Step 1: Write the proportion equation
   156.01 : 215.41 = 100.78 : x
2. Step 2: Convert to fraction form
   156.01/215.41 = 100.78/x
3. Step 3: Cross multiply
   156.01x = 215.41 × 100.78
4. Step 4: Simplify right side
   156.01x = 21,709.02
5. Step 5: Solve for x
   x = 21,709.02/156.01
6. Step 6: Final answer
   x = 139.15