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Finding the Fourth Proportional to 1,390.62, 1,918.14 and 830.72

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Solution

The fourth proportional to 1,390.62, 1,918.14 and 830.72 is: 1,145.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.62 : 1,918.14 = 830.72 : x
  2. Step 2: Convert to fraction form
    1,390.62/1,918.14 = 830.72/x
  3. Step 3: Cross multiply
    1,390.62x = 1,918.14 × 830.72
  4. Step 4: Simplify right side
    1,390.62x = 1,593,437.26
  5. Step 5: Solve for x
    x = 1,593,437.26/1,390.62
  6. Step 6: Final answer
    x = 1,145.85

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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.