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Finding the Fourth Proportional to 1,411.20, 1,947.28 and 781.64

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Solution

The fourth proportional to 1,411.20, 1,947.28 and 781.64 is: 1,078.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,411.20 : 1,947.28 = 781.64 : x
  2. Step 2: Convert to fraction form
    1,411.20/1,947.28 = 781.64/x
  3. Step 3: Cross multiply
    1,411.20x = 1,947.28 × 781.64
  4. Step 4: Simplify right side
    1,411.20x = 1,522,071.94
  5. Step 5: Solve for x
    x = 1,522,071.94/1,411.20
  6. Step 6: Final answer
    x = 1,078.57

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.