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Finding the Fourth Proportional to 781.65, 1,172.61 and 319.68

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Solution

The fourth proportional to 781.65, 1,172.61 and 319.68 is: 479.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.65 : 1,172.61 = 319.68 : x
  2. Step 2: Convert to fraction form
    781.65/1,172.61 = 319.68/x
  3. Step 3: Cross multiply
    781.65x = 1,172.61 × 319.68
  4. Step 4: Simplify right side
    781.65x = 374,859.96
  5. Step 5: Solve for x
    x = 374,859.96/781.65
  6. Step 6: Final answer
    x = 479.58

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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.