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Finding the Fourth Proportional to 781.67, 1,172.55 and 261.65

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Solution

The fourth proportional to 781.67, 1,172.55 and 261.65 is: 392.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.67 : 1,172.55 = 261.65 : x
  2. Step 2: Convert to fraction form
    781.67/1,172.55 = 261.65/x
  3. Step 3: Cross multiply
    781.67x = 1,172.55 × 261.65
  4. Step 4: Simplify right side
    781.67x = 306,795.02
  5. Step 5: Solve for x
    x = 306,795.02/781.67
  6. Step 6: Final answer
    x = 392.49

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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.