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Finding the Fourth Proportional to 1,428.40, 2,142.20 and 647.96

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Solution

The fourth proportional to 1,428.40, 2,142.20 and 647.96 is: 971.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,428.40 : 2,142.20 = 647.96 : x
  2. Step 2: Convert to fraction form
    1,428.40/2,142.20 = 647.96/x
  3. Step 3: Cross multiply
    1,428.40x = 2,142.20 × 647.96
  4. Step 4: Simplify right side
    1,428.40x = 1,388,059.91
  5. Step 5: Solve for x
    x = 1,388,059.91/1,428.40
  6. Step 6: Final answer
    x = 971.76

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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.