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Finding the Fourth Proportional to 685.12, 1,026.96 and 319.60

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Solution

The fourth proportional to 685.12, 1,026.96 and 319.60 is: 479.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.12 : 1,026.96 = 319.60 : x
  2. Step 2: Convert to fraction form
    685.12/1,026.96 = 319.60/x
  3. Step 3: Cross multiply
    685.12x = 1,026.96 × 319.60
  4. Step 4: Simplify right side
    685.12x = 328,216.42
  5. Step 5: Solve for x
    x = 328,216.42/685.12
  6. Step 6: Final answer
    x = 479.06

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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.