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Finding the Fourth Proportional to 1,281.30, 1,920.68 and 817.64

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Solution

The fourth proportional to 1,281.30, 1,920.68 and 817.64 is: 1,225.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,281.30 : 1,920.68 = 817.64 : x
  2. Step 2: Convert to fraction form
    1,281.30/1,920.68 = 817.64/x
  3. Step 3: Cross multiply
    1,281.30x = 1,920.68 × 817.64
  4. Step 4: Simplify right side
    1,281.30x = 1,570,424.80
  5. Step 5: Solve for x
    x = 1,570,424.80/1,281.30
  6. Step 6: Final answer
    x = 1,225.65

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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.