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Finding the Fourth Proportional to 1,387.32, 2,079.70 and 521.08

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Solution

The fourth proportional to 1,387.32, 2,079.70 and 521.08 is: 781.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.32 : 2,079.70 = 521.08 : x
  2. Step 2: Convert to fraction form
    1,387.32/2,079.70 = 521.08/x
  3. Step 3: Cross multiply
    1,387.32x = 2,079.70 × 521.08
  4. Step 4: Simplify right side
    1,387.32x = 1,083,690.08
  5. Step 5: Solve for x
    x = 1,083,690.08/1,387.32
  6. Step 6: Final answer
    x = 781.14

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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.