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Finding the Fourth Proportional to 1,239.89, 1,860.08 and 418.40

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Solution

The fourth proportional to 1,239.89, 1,860.08 and 418.40 is: 627.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,239.89 : 1,860.08 = 418.40 : x
  2. Step 2: Convert to fraction form
    1,239.89/1,860.08 = 418.40/x
  3. Step 3: Cross multiply
    1,239.89x = 1,860.08 × 418.40
  4. Step 4: Simplify right side
    1,239.89x = 778,255.41
  5. Step 5: Solve for x
    x = 778,255.41/1,239.89
  6. Step 6: Final answer
    x = 627.68

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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.