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Finding the Fourth Proportional to 1,212.89, 1,818.95 and 390.99

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Solution

The fourth proportional to 1,212.89, 1,818.95 and 390.99 is: 586.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,212.89 : 1,818.95 = 390.99 : x
  2. Step 2: Convert to fraction form
    1,212.89/1,818.95 = 390.99/x
  3. Step 3: Cross multiply
    1,212.89x = 1,818.95 × 390.99
  4. Step 4: Simplify right side
    1,212.89x = 711,191.26
  5. Step 5: Solve for x
    x = 711,191.26/1,212.89
  6. Step 6: Final answer
    x = 586.36

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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.