Finding the Fourth Proportional to 78.98, 108.86 and 65.84

Step by Step Solution

1. Step 1: Write the proportion equation
   78.98 : 108.86 = 65.84 : x
2. Step 2: Convert to fraction form
   78.98/108.86 = 65.84/x
3. Step 3: Cross multiply
   78.98x = 108.86 × 65.84
4. Step 4: Simplify right side
   78.98x = 7,167.34
5. Step 5: Solve for x
   x = 7,167.34/78.98
6. Step 6: Final answer
   x = 90.75