Finding the Fourth Proportional to 342.78, 514.16 and 99.31

Step by Step Solution

1. Step 1: Write the proportion equation
   342.78 : 514.16 = 99.31 : x
2. Step 2: Convert to fraction form
   342.78/514.16 = 99.31/x
3. Step 3: Cross multiply
   342.78x = 514.16 × 99.31
4. Step 4: Simplify right side
   342.78x = 51,061.34
5. Step 5: Solve for x
   x = 51,061.34/342.78
6. Step 6: Final answer
   x = 148.96