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Finding the Fourth Proportional to 1,421.86, 2,132.78 and 642.13

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Solution

The fourth proportional to 1,421.86, 2,132.78 and 642.13 is: 963.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,421.86 : 2,132.78 = 642.13 : x
  2. Step 2: Convert to fraction form
    1,421.86/2,132.78 = 642.13/x
  3. Step 3: Cross multiply
    1,421.86x = 2,132.78 × 642.13
  4. Step 4: Simplify right side
    1,421.86x = 1,369,529.76
  5. Step 5: Solve for x
    x = 1,369,529.76/1,421.86
  6. Step 6: Final answer
    x = 963.20

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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.