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Finding the Fourth Proportional to 1,428.78, 1,969.91 and 1,215.88

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Solution

The fourth proportional to 1,428.78, 1,969.91 and 1,215.88 is: 1,676.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,428.78 : 1,969.91 = 1,215.88 : x
  2. Step 2: Convert to fraction form
    1,428.78/1,969.91 = 1,215.88/x
  3. Step 3: Cross multiply
    1,428.78x = 1,969.91 × 1,215.88
  4. Step 4: Simplify right side
    1,428.78x = 2,395,174.17
  5. Step 5: Solve for x
    x = 2,395,174.17/1,428.78
  6. Step 6: Final answer
    x = 1,676.38

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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.