Finding the Fourth Proportional to 1,385.60, 1,911.96 and 764.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.60 : 1,911.96 = 764.56 : x
2. Step 2: Convert to fraction form
   1,385.60/1,911.96 = 764.56/x
3. Step 3: Cross multiply
   1,385.60x = 1,911.96 × 764.56
4. Step 4: Simplify right side
   1,385.60x = 1,461,808.14
5. Step 5: Solve for x
   x = 1,461,808.14/1,385.60
6. Step 6: Final answer
   x = 1,055.00