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Finding the Fourth Proportional to 685.12, 1,026.32 and 319.40

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Solution

The fourth proportional to 685.12, 1,026.32 and 319.40 is: 478.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.12 : 1,026.32 = 319.40 : x
  2. Step 2: Convert to fraction form
    685.12/1,026.32 = 319.40/x
  3. Step 3: Cross multiply
    685.12x = 1,026.32 × 319.40
  4. Step 4: Simplify right side
    685.12x = 327,806.61
  5. Step 5: Solve for x
    x = 327,806.61/685.12
  6. Step 6: Final answer
    x = 478.47

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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.