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Finding the Fourth Proportional to 1,387.80, 2,081.16 and 521.64

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Solution

The fourth proportional to 1,387.80, 2,081.16 and 521.64 is: 782.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.80 : 2,081.16 = 521.64 : x
  2. Step 2: Convert to fraction form
    1,387.80/2,081.16 = 521.64/x
  3. Step 3: Cross multiply
    1,387.80x = 2,081.16 × 521.64
  4. Step 4: Simplify right side
    1,387.80x = 1,085,616.30
  5. Step 5: Solve for x
    x = 1,085,616.30/1,387.80
  6. Step 6: Final answer
    x = 782.26

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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.