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Finding the Fourth Proportional to 780.12, 1,169.56 and 389.93

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Solution

The fourth proportional to 780.12, 1,169.56 and 389.93 is: 584.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.12 : 1,169.56 = 389.93 : x
  2. Step 2: Convert to fraction form
    780.12/1,169.56 = 389.93/x
  3. Step 3: Cross multiply
    780.12x = 1,169.56 × 389.93
  4. Step 4: Simplify right side
    780.12x = 456,041.17
  5. Step 5: Solve for x
    x = 456,041.17/780.12
  6. Step 6: Final answer
    x = 584.58

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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.