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Finding the Fourth Proportional to 3,120, 4,680 and 1,388.58

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Solution

The fourth proportional to 3,120, 4,680 and 1,388.58 is: 2,082.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    3,120 : 4,680 = 1,388.58 : x
  2. Step 2: Convert to fraction form
    3,120/4,680 = 1,388.58/x
  3. Step 3: Cross multiply
    3,120x = 4,680 × 1,388.58
  4. Step 4: Simplify right side
    3,120x = 6,498,554.40
  5. Step 5: Solve for x
    x = 6,498,554.40/3,120
  6. Step 6: Final answer
    x = 2,082.87

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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.