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Finding the Fourth Proportional to 1,242.61, 1,863.61 and 420.86

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Solution

The fourth proportional to 1,242.61, 1,863.61 and 420.86 is: 631.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,242.61 : 1,863.61 = 420.86 : x
  2. Step 2: Convert to fraction form
    1,242.61/1,863.61 = 420.86/x
  3. Step 3: Cross multiply
    1,242.61x = 1,863.61 × 420.86
  4. Step 4: Simplify right side
    1,242.61x = 784,322.51
  5. Step 5: Solve for x
    x = 784,322.51/1,242.61
  6. Step 6: Final answer
    x = 631.19

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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.