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Finding the Fourth Proportional to 780.40, 1,169.80 and 318.12

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Solution

The fourth proportional to 780.40, 1,169.80 and 318.12 is: 476.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.40 : 1,169.80 = 318.12 : x
  2. Step 2: Convert to fraction form
    780.40/1,169.80 = 318.12/x
  3. Step 3: Cross multiply
    780.40x = 1,169.80 × 318.12
  4. Step 4: Simplify right side
    780.40x = 372,136.78
  5. Step 5: Solve for x
    x = 372,136.78/780.40
  6. Step 6: Final answer
    x = 476.85

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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.