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Finding the Fourth Proportional to 685.80, 1,030.28 and 442.80

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Solution

The fourth proportional to 685.80, 1,030.28 and 442.80 is: 665.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.80 : 1,030.28 = 442.80 : x
  2. Step 2: Convert to fraction form
    685.80/1,030.28 = 442.80/x
  3. Step 3: Cross multiply
    685.80x = 1,030.28 × 442.80
  4. Step 4: Simplify right side
    685.80x = 456,207.98
  5. Step 5: Solve for x
    x = 456,207.98/685.80
  6. Step 6: Final answer
    x = 665.22

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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.