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Finding the Fourth Proportional to 860.81, 1,290.74 and 421.92

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Solution

The fourth proportional to 860.81, 1,290.74 and 421.92 is: 632.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.81 : 1,290.74 = 421.92 : x
  2. Step 2: Convert to fraction form
    860.81/1,290.74 = 421.92/x
  3. Step 3: Cross multiply
    860.81x = 1,290.74 × 421.92
  4. Step 4: Simplify right side
    860.81x = 544,586.91
  5. Step 5: Solve for x
    x = 544,586.91/860.81
  6. Step 6: Final answer
    x = 632.65

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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.