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Finding the Fourth Proportional to 813.78, 1,215.72 and 518.93

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Solution

The fourth proportional to 813.78, 1,215.72 and 518.93 is: 775.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.78 : 1,215.72 = 518.93 : x
  2. Step 2: Convert to fraction form
    813.78/1,215.72 = 518.93/x
  3. Step 3: Cross multiply
    813.78x = 1,215.72 × 518.93
  4. Step 4: Simplify right side
    813.78x = 630,870.11
  5. Step 5: Solve for x
    x = 630,870.11/813.78
  6. Step 6: Final answer
    x = 775.24

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.