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Finding the Fourth Proportional to 810.78, 1,215.70 and 445.48

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Solution

The fourth proportional to 810.78, 1,215.70 and 445.48 is: 667.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.78 : 1,215.70 = 445.48 : x
  2. Step 2: Convert to fraction form
    810.78/1,215.70 = 445.48/x
  3. Step 3: Cross multiply
    810.78x = 1,215.70 × 445.48
  4. Step 4: Simplify right side
    810.78x = 541,570.04
  5. Step 5: Solve for x
    x = 541,570.04/810.78
  6. Step 6: Final answer
    x = 667.96

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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.