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Finding the Fourth Proportional to 1,275.68, 1,912.28 and 409.40

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Solution

The fourth proportional to 1,275.68, 1,912.28 and 409.40 is: 613.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,275.68 : 1,912.28 = 409.40 : x
  2. Step 2: Convert to fraction form
    1,275.68/1,912.28 = 409.40/x
  3. Step 3: Cross multiply
    1,275.68x = 1,912.28 × 409.40
  4. Step 4: Simplify right side
    1,275.68x = 782,887.43
  5. Step 5: Solve for x
    x = 782,887.43/1,275.68
  6. Step 6: Final answer
    x = 613.70

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.