Finding the Fourth Proportional to 115.80, 159.72 and 78.98

Step by Step Solution

1. Step 1: Write the proportion equation
   115.80 : 159.72 = 78.98 : x
2. Step 2: Convert to fraction form
   115.80/159.72 = 78.98/x
3. Step 3: Cross multiply
   115.80x = 159.72 × 78.98
4. Step 4: Simplify right side
   115.80x = 12,613.89
5. Step 5: Solve for x
   x = 12,613.89/115.80
6. Step 6: Final answer
   x = 108.93