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Finding the Fourth Proportional to 1,211.88, 1,818 and 390.18

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Solution

The fourth proportional to 1,211.88, 1,818 and 390.18 is: 585.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,211.88 : 1,818 = 390.18 : x
  2. Step 2: Convert to fraction form
    1,211.88/1,818 = 390.18/x
  3. Step 3: Cross multiply
    1,211.88x = 1,818 × 390.18
  4. Step 4: Simplify right side
    1,211.88x = 709,347.24
  5. Step 5: Solve for x
    x = 709,347.24/1,211.88
  6. Step 6: Final answer
    x = 585.33

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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.