Finding the Fourth Proportional to 2,547.80, 3,515.86 and 1,428.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,547.80 : 3,515.86 = 1,428.72 : x
2. Step 2: Convert to fraction form
   2,547.80/3,515.86 = 1,428.72/x
3. Step 3: Cross multiply
   2,547.80x = 3,515.86 × 1,428.72
4. Step 4: Simplify right side
   2,547.80x = 5,023,179.50
5. Step 5: Solve for x
   x = 5,023,179.50/2,547.80
6. Step 6: Final answer
   x = 1,971.58