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Finding the Fourth Proportional to 999.65, 1,380.14 and 645.75

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Solution

The fourth proportional to 999.65, 1,380.14 and 645.75 is: 891.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    999.65 : 1,380.14 = 645.75 : x
  2. Step 2: Convert to fraction form
    999.65/1,380.14 = 645.75/x
  3. Step 3: Cross multiply
    999.65x = 1,380.14 × 645.75
  4. Step 4: Simplify right side
    999.65x = 891,222.18
  5. Step 5: Solve for x
    x = 891,222.18/999.65
  6. Step 6: Final answer
    x = 891.54

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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.