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Finding the Fourth Proportional to 805.74, 1,208.79 and 318.80

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Solution

The fourth proportional to 805.74, 1,208.79 and 318.80 is: 478.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    805.74 : 1,208.79 = 318.80 : x
  2. Step 2: Convert to fraction form
    805.74/1,208.79 = 318.80/x
  3. Step 3: Cross multiply
    805.74x = 1,208.79 × 318.80
  4. Step 4: Simplify right side
    805.74x = 385,356.21
  5. Step 5: Solve for x
    x = 385,356.21/805.74
  6. Step 6: Final answer
    x = 478.26

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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.