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Finding the Fourth Proportional to 687.99, 949.40 and 393.20

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Solution

The fourth proportional to 687.99, 949.40 and 393.20 is: 542.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.99 : 949.40 = 393.20 : x
  2. Step 2: Convert to fraction form
    687.99/949.40 = 393.20/x
  3. Step 3: Cross multiply
    687.99x = 949.40 × 393.20
  4. Step 4: Simplify right side
    687.99x = 373,304.08
  5. Step 5: Solve for x
    x = 373,304.08/687.99
  6. Step 6: Final answer
    x = 542.60

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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.