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Finding the Fourth Proportional to 1,240.78, 1,861.20 and 419.08

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Solution

The fourth proportional to 1,240.78, 1,861.20 and 419.08 is: 628.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,240.78 : 1,861.20 = 419.08 : x
  2. Step 2: Convert to fraction form
    1,240.78/1,861.20 = 419.08/x
  3. Step 3: Cross multiply
    1,240.78x = 1,861.20 × 419.08
  4. Step 4: Simplify right side
    1,240.78x = 779,991.70
  5. Step 5: Solve for x
    x = 779,991.70/1,240.78
  6. Step 6: Final answer
    x = 628.63

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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.