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Finding the Fourth Proportional to 687.80, 949.18 and 389.05

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Solution

The fourth proportional to 687.80, 949.18 and 389.05 is: 536.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.80 : 949.18 = 389.05 : x
  2. Step 2: Convert to fraction form
    687.80/949.18 = 389.05/x
  3. Step 3: Cross multiply
    687.80x = 949.18 × 389.05
  4. Step 4: Simplify right side
    687.80x = 369,278.91
  5. Step 5: Solve for x
    x = 369,278.91/687.80
  6. Step 6: Final answer
    x = 536.90

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.