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Finding the Fourth Proportional to 816.32, 1,223.28 and 643.40

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Solution

The fourth proportional to 816.32, 1,223.28 and 643.40 is: 964.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    816.32 : 1,223.28 = 643.40 : x
  2. Step 2: Convert to fraction form
    816.32/1,223.28 = 643.40/x
  3. Step 3: Cross multiply
    816.32x = 1,223.28 × 643.40
  4. Step 4: Simplify right side
    816.32x = 787,058.35
  5. Step 5: Solve for x
    x = 787,058.35/816.32
  6. Step 6: Final answer
    x = 964.15

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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.