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Finding the Fourth Proportional to 688.40, 949.90 and 389.64

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Solution

The fourth proportional to 688.40, 949.90 and 389.64 is: 537.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    688.40 : 949.90 = 389.64 : x
  2. Step 2: Convert to fraction form
    688.40/949.90 = 389.64/x
  3. Step 3: Cross multiply
    688.40x = 949.90 × 389.64
  4. Step 4: Simplify right side
    688.40x = 370,119.04
  5. Step 5: Solve for x
    x = 370,119.04/688.40
  6. Step 6: Final answer
    x = 537.65

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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.