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Finding the Fourth Proportional to 1,390.85, 2,084.65 and 812.51

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Solution

The fourth proportional to 1,390.85, 2,084.65 and 812.51 is: 1,217.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.85 : 2,084.65 = 812.51 : x
  2. Step 2: Convert to fraction form
    1,390.85/2,084.65 = 812.51/x
  3. Step 3: Cross multiply
    1,390.85x = 2,084.65 × 812.51
  4. Step 4: Simplify right side
    1,390.85x = 1,693,798.97
  5. Step 5: Solve for x
    x = 1,693,798.97/1,390.85
  6. Step 6: Final answer
    x = 1,217.82

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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.