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Finding the Fourth Proportional to 781.40, 1,172.90 and 416.50

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Solution

The fourth proportional to 781.40, 1,172.90 and 416.50 is: 625.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.40 : 1,172.90 = 416.50 : x
  2. Step 2: Convert to fraction form
    781.40/1,172.90 = 416.50/x
  3. Step 3: Cross multiply
    781.40x = 1,172.90 × 416.50
  4. Step 4: Simplify right side
    781.40x = 488,512.85
  5. Step 5: Solve for x
    x = 488,512.85/781.40
  6. Step 6: Final answer
    x = 625.18

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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.