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Finding the Fourth Proportional to 781.49, 1,172.07 and 318.81

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Solution

The fourth proportional to 781.49, 1,172.07 and 318.81 is: 478.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.49 : 1,172.07 = 318.81 : x
  2. Step 2: Convert to fraction form
    781.49/1,172.07 = 318.81/x
  3. Step 3: Cross multiply
    781.49x = 1,172.07 × 318.81
  4. Step 4: Simplify right side
    781.49x = 373,672.03
  5. Step 5: Solve for x
    x = 373,672.03/781.49
  6. Step 6: Final answer
    x = 478.15

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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.