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Finding the Fourth Proportional to 1,287.60, 1,929.84 and 636.80

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Solution

The fourth proportional to 1,287.60, 1,929.84 and 636.80 is: 954.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.60 : 1,929.84 = 636.80 : x
  2. Step 2: Convert to fraction form
    1,287.60/1,929.84 = 636.80/x
  3. Step 3: Cross multiply
    1,287.60x = 1,929.84 × 636.80
  4. Step 4: Simplify right side
    1,287.60x = 1,228,922.11
  5. Step 5: Solve for x
    x = 1,228,922.11/1,287.60
  6. Step 6: Final answer
    x = 954.43

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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.