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Finding the Fourth Proportional to 643.90, 964.80 and 399.76

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Solution

The fourth proportional to 643.90, 964.80 and 399.76 is: 598.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.90 : 964.80 = 399.76 : x
  2. Step 2: Convert to fraction form
    643.90/964.80 = 399.76/x
  3. Step 3: Cross multiply
    643.90x = 964.80 × 399.76
  4. Step 4: Simplify right side
    643.90x = 385,688.45
  5. Step 5: Solve for x
    x = 385,688.45/643.90
  6. Step 6: Final answer
    x = 598.99

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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.