Finding the Fourth Proportional to 1,275.10, 1,759.59 and 715.60

Step by Step Solution

1. Step 1: Write the proportion equation
   1,275.10 : 1,759.59 = 715.60 : x
2. Step 2: Convert to fraction form
   1,275.10/1,759.59 = 715.60/x
3. Step 3: Cross multiply
   1,275.10x = 1,759.59 × 715.60
4. Step 4: Simplify right side
   1,275.10x = 1,259,162.60
5. Step 5: Solve for x
   x = 1,259,162.60/1,275.10
6. Step 6: Final answer
   x = 987.50