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Finding the Fourth Proportional to 613.60, 920.40 and 419.20

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Solution

The fourth proportional to 613.60, 920.40 and 419.20 is: 628.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    613.60 : 920.40 = 419.20 : x
  2. Step 2: Convert to fraction form
    613.60/920.40 = 419.20/x
  3. Step 3: Cross multiply
    613.60x = 920.40 × 419.20
  4. Step 4: Simplify right side
    613.60x = 385,831.68
  5. Step 5: Solve for x
    x = 385,831.68/613.60
  6. Step 6: Final answer
    x = 628.80

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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.