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Finding the Fourth Proportional to 1,425.80, 2,138.70 and 657.80

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Solution

The fourth proportional to 1,425.80, 2,138.70 and 657.80 is: 986.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,425.80 : 2,138.70 = 657.80 : x
  2. Step 2: Convert to fraction form
    1,425.80/2,138.70 = 657.80/x
  3. Step 3: Cross multiply
    1,425.80x = 2,138.70 × 657.80
  4. Step 4: Simplify right side
    1,425.80x = 1,406,836.86
  5. Step 5: Solve for x
    x = 1,406,836.86/1,425.80
  6. Step 6: Final answer
    x = 986.70

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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.