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Finding the Fourth Proportional to 1,438.20, 1,984.91 and 840.60

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Solution

The fourth proportional to 1,438.20, 1,984.91 and 840.60 is: 1,160.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,438.20 : 1,984.91 = 840.60 : x
  2. Step 2: Convert to fraction form
    1,438.20/1,984.91 = 840.60/x
  3. Step 3: Cross multiply
    1,438.20x = 1,984.91 × 840.60
  4. Step 4: Simplify right side
    1,438.20x = 1,668,511.14
  5. Step 5: Solve for x
    x = 1,668,511.14/1,438.20
  6. Step 6: Final answer
    x = 1,160.14

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.