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Finding the Fourth Proportional to 781.07, 1,170.72 and 390.48

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Solution

The fourth proportional to 781.07, 1,170.72 and 390.48 is: 585.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.07 : 1,170.72 = 390.48 : x
  2. Step 2: Convert to fraction form
    781.07/1,170.72 = 390.48/x
  3. Step 3: Cross multiply
    781.07x = 1,170.72 × 390.48
  4. Step 4: Simplify right side
    781.07x = 457,142.75
  5. Step 5: Solve for x
    x = 457,142.75/781.07
  6. Step 6: Final answer
    x = 585.28

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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.