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Finding the Fourth Proportional to 1,124.80, 1,687.20 and 638.80

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Solution

The fourth proportional to 1,124.80, 1,687.20 and 638.80 is: 958.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,124.80 : 1,687.20 = 638.80 : x
  2. Step 2: Convert to fraction form
    1,124.80/1,687.20 = 638.80/x
  3. Step 3: Cross multiply
    1,124.80x = 1,687.20 × 638.80
  4. Step 4: Simplify right side
    1,124.80x = 1,077,783.36
  5. Step 5: Solve for x
    x = 1,077,783.36/1,124.80
  6. Step 6: Final answer
    x = 958.20

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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.