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Finding the Fourth Proportional to 1,212.65, 1,818.57 and 390.72

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Solution

The fourth proportional to 1,212.65, 1,818.57 and 390.72 is: 585.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,212.65 : 1,818.57 = 390.72 : x
  2. Step 2: Convert to fraction form
    1,212.65/1,818.57 = 390.72/x
  3. Step 3: Cross multiply
    1,212.65x = 1,818.57 × 390.72
  4. Step 4: Simplify right side
    1,212.65x = 710,551.67
  5. Step 5: Solve for x
    x = 710,551.67/1,212.65
  6. Step 6: Final answer
    x = 585.95

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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.