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Finding the Fourth Proportional to 781.79, 1,172.88 and 261.81

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Solution

The fourth proportional to 781.79, 1,172.88 and 261.81 is: 392.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.79 : 1,172.88 = 261.81 : x
  2. Step 2: Convert to fraction form
    781.79/1,172.88 = 261.81/x
  3. Step 3: Cross multiply
    781.79x = 1,172.88 × 261.81
  4. Step 4: Simplify right side
    781.79x = 307,071.71
  5. Step 5: Solve for x
    x = 307,071.71/781.79
  6. Step 6: Final answer
    x = 392.78

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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.