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Finding the Fourth Proportional to 810.42, 1,215.08 and 393.72

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Solution

The fourth proportional to 810.42, 1,215.08 and 393.72 is: 590.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.42 : 1,215.08 = 393.72 : x
  2. Step 2: Convert to fraction form
    810.42/1,215.08 = 393.72/x
  3. Step 3: Cross multiply
    810.42x = 1,215.08 × 393.72
  4. Step 4: Simplify right side
    810.42x = 478,401.30
  5. Step 5: Solve for x
    x = 478,401.30/810.42
  6. Step 6: Final answer
    x = 590.31

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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.