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Finding the Fourth Proportional to 1,306.78, 1,958.80 and 612.90

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Solution

The fourth proportional to 1,306.78, 1,958.80 and 612.90 is: 918.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,306.78 : 1,958.80 = 612.90 : x
  2. Step 2: Convert to fraction form
    1,306.78/1,958.80 = 612.90/x
  3. Step 3: Cross multiply
    1,306.78x = 1,958.80 × 612.90
  4. Step 4: Simplify right side
    1,306.78x = 1,200,548.14
  5. Step 5: Solve for x
    x = 1,200,548.14/1,306.78
  6. Step 6: Final answer
    x = 918.70

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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.