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Finding the Fourth Proportional to 909.80, 1,364.70 and 861.80

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Solution

The fourth proportional to 909.80, 1,364.70 and 861.80 is: 1,292.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    909.80 : 1,364.70 = 861.80 : x
  2. Step 2: Convert to fraction form
    909.80/1,364.70 = 861.80/x
  3. Step 3: Cross multiply
    909.80x = 1,364.70 × 861.80
  4. Step 4: Simplify right side
    909.80x = 1,176,098.46
  5. Step 5: Solve for x
    x = 1,176,098.46/909.80
  6. Step 6: Final answer
    x = 1,292.70

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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.