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Finding the Fourth Proportional to 1,209.70, 1,815.15 and 690.10

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Solution

The fourth proportional to 1,209.70, 1,815.15 and 690.10 is: 1,035.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.70 : 1,815.15 = 690.10 : x
  2. Step 2: Convert to fraction form
    1,209.70/1,815.15 = 690.10/x
  3. Step 3: Cross multiply
    1,209.70x = 1,815.15 × 690.10
  4. Step 4: Simplify right side
    1,209.70x = 1,252,635.02
  5. Step 5: Solve for x
    x = 1,252,635.02/1,209.70
  6. Step 6: Final answer
    x = 1,035.49

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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.