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Finding the Fourth Proportional to 1,242.72, 1,863.90 and 420.84

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Solution

The fourth proportional to 1,242.72, 1,863.90 and 420.84 is: 631.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,242.72 : 1,863.90 = 420.84 : x
  2. Step 2: Convert to fraction form
    1,242.72/1,863.90 = 420.84/x
  3. Step 3: Cross multiply
    1,242.72x = 1,863.90 × 420.84
  4. Step 4: Simplify right side
    1,242.72x = 784,403.68
  5. Step 5: Solve for x
    x = 784,403.68/1,242.72
  6. Step 6: Final answer
    x = 631.20

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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.