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Finding the Fourth Proportional to 1,390.85, 1,918.45 and 830.87

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Solution

The fourth proportional to 1,390.85, 1,918.45 and 830.87 is: 1,146.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.85 : 1,918.45 = 830.87 : x
  2. Step 2: Convert to fraction form
    1,390.85/1,918.45 = 830.87/x
  3. Step 3: Cross multiply
    1,390.85x = 1,918.45 × 830.87
  4. Step 4: Simplify right side
    1,390.85x = 1,593,985.27
  5. Step 5: Solve for x
    x = 1,593,985.27/1,390.85
  6. Step 6: Final answer
    x = 1,146.06

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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.