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Finding the Fourth Proportional to 1,124.40, 1,687.80 and 638.40

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Solution

The fourth proportional to 1,124.40, 1,687.80 and 638.40 is: 958.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,124.40 : 1,687.80 = 638.40 : x
  2. Step 2: Convert to fraction form
    1,124.40/1,687.80 = 638.40/x
  3. Step 3: Cross multiply
    1,124.40x = 1,687.80 × 638.40
  4. Step 4: Simplify right side
    1,124.40x = 1,077,491.52
  5. Step 5: Solve for x
    x = 1,077,491.52/1,124.40
  6. Step 6: Final answer
    x = 958.28

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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.