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Finding the Fourth Proportional to 1,311.90, 1,808.04 and 938.90

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Solution

The fourth proportional to 1,311.90, 1,808.04 and 938.90 is: 1,293.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.90 : 1,808.04 = 938.90 : x
  2. Step 2: Convert to fraction form
    1,311.90/1,808.04 = 938.90/x
  3. Step 3: Cross multiply
    1,311.90x = 1,808.04 × 938.90
  4. Step 4: Simplify right side
    1,311.90x = 1,697,568.76
  5. Step 5: Solve for x
    x = 1,697,568.76/1,311.90
  6. Step 6: Final answer
    x = 1,293.98

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.