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Finding the Fourth Proportional to 1,394.60, 2,091.92 and 420.72

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Solution

The fourth proportional to 1,394.60, 2,091.92 and 420.72 is: 631.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,394.60 : 2,091.92 = 420.72 : x
  2. Step 2: Convert to fraction form
    1,394.60/2,091.92 = 420.72/x
  3. Step 3: Cross multiply
    1,394.60x = 2,091.92 × 420.72
  4. Step 4: Simplify right side
    1,394.60x = 880,112.58
  5. Step 5: Solve for x
    x = 880,112.58/1,394.60
  6. Step 6: Final answer
    x = 631.09

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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.