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Finding the Fourth Proportional to 810.79, 1,215.16 and 518.20

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Solution

The fourth proportional to 810.79, 1,215.16 and 518.20 is: 776.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.79 : 1,215.16 = 518.20 : x
  2. Step 2: Convert to fraction form
    810.79/1,215.16 = 518.20/x
  3. Step 3: Cross multiply
    810.79x = 1,215.16 × 518.20
  4. Step 4: Simplify right side
    810.79x = 629,693.32
  5. Step 5: Solve for x
    x = 629,693.32/810.79
  6. Step 6: Final answer
    x = 776.64

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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.