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Finding the Fourth Proportional to 1,330.12, 1,992.40 and 780.64

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Solution

The fourth proportional to 1,330.12, 1,992.40 and 780.64 is: 1,169.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,330.12 : 1,992.40 = 780.64 : x
  2. Step 2: Convert to fraction form
    1,330.12/1,992.40 = 780.64/x
  3. Step 3: Cross multiply
    1,330.12x = 1,992.40 × 780.64
  4. Step 4: Simplify right side
    1,330.12x = 1,555,347.14
  5. Step 5: Solve for x
    x = 1,555,347.14/1,330.12
  6. Step 6: Final answer
    x = 1,169.33

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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.